You’re not alone. No one in my office - a higher education english department - got this one either. I’m guessing the poster either “told” it wrong, or has a much different version of humor than most of western civilization. Sorry if I offended.
I think the humor is in what the nuns would do with the soap to wear it (down). I could be wrong, tho.
Why do people refer to a womans “that time of the month” as P.M.S?
“Mad Cow Disease” was already taken.
What did the fish say when it ran into a concrete wall?
“Damn!”
A priest is walking through his parish one day, and finds himself at the waterfront. He watches a fisherman work on his boat for a little while, when the fisherman sees him and invites him to go fishing.
“I’ve never gone fishing before,” the priest say, “I’d love to go.”
The two men are out fishing and having a great time, when the priest hooks a big sea bass. As he reels it in, the fisherman helps with the net.
In his excitement, the fisherman yells out, “Look at the size of that sonofabitch!”
“Young, man,” the priest chastises, “Your language, please.”
Embarrassed, the fisherman attempts to cover his tracks, “No, Father, you don’t understand. That’s what kind of a fish this is. It’s a sonofabitch fish.”
Not knowing anything about fish, the priest accepts this. So he goes back to the rectory with his fish and presents it to the monsignor.
“Monsignor, look at this big sonofabitch I just caught.”
“Father,” the monsignor says, “you are in a house of the Lord.”
“No, you don’t understand, Monsignor. That’s what this fish is called. It’s a sonofabitch fish.”
“Oh, I understand. Well that certainly is one big sonofabitch. Tell you what, I’ll clean that sonofabitch and I’ll ask the mother superior to fry it up for dinner.”
They go trudging to the kitchen where the mother superior is beginning supper prepartaions.
The monsignor adresses her, “Mother Superior, Father O’Callahan caught this big sonofabitch, and I cleaned it. We were hoping you might fry this sonofabitch up for supper tonight.”
The mother superior is aghast, “Monsignor, what language.”
“No, mother superior, you don’t understand. That’s what this fish is called. It’s a sonofabith fish.”
“Oh, I understand. Certainly, I’d be happy to fry that sonofabitch up.”
As she is preparing the fish, the pope drops by for supper. The mother superior serves the fish and she, the monsignor, the priest and the pope all enjoy it immensly.
The pope inquires, "Where did this fish come from, it certainly was tasty.
The priest says, “Your holiness, I caught that sonofabitch.”
The monsignor say, “And I cleaned that sonofabitch.”
The mother superior says, “And your holiness, I cooked that sonofabitch.”
The pope looks at them with a steely gaze. He takes off his hat and sets on the table. He leans back in his chair and says, “You know, … you fuckers are all right.”
How about …
Losing a wife can be hard.
In my case it was damn near impossible.
Guy goes to hell and is met by the devil, who explains that the punishments are changed every thousand years and he is to select his first punishment.
First room has a young guy on the wall being whipped. The new guy not keen on this asks to see the next room. The next room has a middle aged guy being tortured with fire.
The new guy immediately asks to see the third room. It has an really old guy chained to the wall getting a blow job from a gorgeous blonde.
The guy jumps at the chance and takes the room.
The devil walks into the room taps the blonde on the shoulder and says “okay, you can stop now. You’ve been relieved”.
Two Indians were riding across the plains on their ponies. They pulled to a stop to check if they were being followed.
The first one climbs down off of his pony and puts his ear to the ground.
The second one asks the first one what he hears.
The first one says “buffalo come.”
The second one says “I see nothing moving for miles, how do you know this?”
The first one replies, putting his hand to his cheek: “face all sticky”
Three mice moved into a new bathroom, after being evicted from their previous home by the owners. One mouse moved into the sink, the other into the bath, and the last into the toilet.
They arranged to have an important meeting the following morning at exactly 8.00am. The mice from the sink and the bath arrived bang on time, but the mouse from the toilet still hadn’t arrived at 9.00am.
Concerned, the two other mice decided to head for the toilet to see what had happened to their friend. As they approached the toilet, they noticed him lying in a heap on the floor - beaten and battered.
“What happened to you?” they asked. The battered mouse replied: “Well, first it rained,then it thundered, then a fuckin’ big brown log hit me on the bastard head”!
I’m saving my favorite for later 
Here’s my (somewhat) different version…
A Koala Bear is on a trip and is feeling a bit randy and starts asking around the street if anyone would mind having sex with him.
A prostitute, noticing this, says that she will oblige so upstairs they go and have at it.
The Koala dives in and proceeds to give the prostitute head for awhile. After that he proceeds to have sex with her till he finally climaxes.
After he rests a bit he gets up and starts walking out of the room.
“Just where do you think you’re going? You owe me money.” says the prostitute.
“Really?” says the Koala. “Why?”
“Because that’s what prostitutes do. Look it up!”
So the Koala grabs a dictionary and looks up prostitute and sure enough it says to have sex for money. With that the Koala drops the dictionary and heads for the door.
“Where are you going,” asks the prostitute?
“I’m doing what Koala’s do. Look it up.”
So the prostitute grabs the dictionary and looks up Koala:
Def: Furry creature that eats, roots, shoots and leaves.
A woman dies and goes to heaven. St. Peter meets her at the gate, and welcomes her to heaven.
“But I’m not supposed to be here, I’m supposed to be in Summerland.”
St. Peter looks at her and says, “Are you a pagan?”
The woman replies, “Yes, I am.”
St. Peter says, “Oh, well then you want to be over here.” He starts walking away.
The woman follows him until they come to a large open field, surrounded by forest. She sees people running and dancing and having sex and talking to trees, and it’s exactly how she’d pictured Summerland.
She looks around a bit more and sees a group of people off to the side, all wailing, and rending their clothes, and cursing the people having fun. She asks St. Peter who they are, and he replies, “They’re fundamentalists.”
“But why are they here? I mean, they’re in heaven, shouldn’t they be doing something fun?” She asks.
St. Peter replies, “Actually they’re in hell. God doesn’t like to be told what he thinks.”
And my favourite blonde joke:
Two blondes are walking in the woods and they come upon a set of tracks.
The first blonde looks at them and says they’re bear tracks.
The second blonde says, “No, they’re moose tracks.”
The first blonde shakes her head. “I don’t know, I’m pretty sure they’re bear tracks.”
The second blonde says, “I’m positive they’re moose tracks.”
They were still arguing when the train hit them.
Pierre, a French Fighter Pilot, and his girlfriend Marie decided one day to have a romantic picnic along the shore of the River Seine. After picking a spot and eating the lunch that Marie has prepared, they get down to a little snuggling.
As the action heats up Marie, with her eyes closed in rapture, whispers in Pierre’s ear “Pierre, kiss me.”
Pierre takes a glass of red wine and throws it in Marie’s face and begins to kiss her. Marie sputters and demands, “Pierre! What are you doing?”
Pierre responds, “I am Pierre, a French Fighter Pilot, and when I have red meat I like to have red wine.” After saying this he begins to passionately kiss Marie.
Things really start to heat up and Marie whispers, “Pierre, kiss me lower.”
Pierre suddenly rips Marie’s shirt open, grabs an open bottle of white wine and dumps it over Marie’s breasts. “Pierre, what are you doing?”
“I am a French Fighter Pilot, and when I have white meat I like to have white wine.”
Marie thinks this is a little wierd and kinky but kinda neat as well. Things really start to heat up and Marie pants “Pierre, kiss me lower.”
Pierre grabs a glass of cognac, rips off Marie’s panties, dumps the glass on her bush, and lights it on fire!
“Pierre!! What the hell are you doing?” screams Marie as she frantically tries to put out the fire.
“My name is Pierre, I am a French Fighter Pilot and when I go down, IT’S IN FLAMES.”
A teenage boy comes home from school one day and says hello to his mother in the kitchen. She asks him what he did in school. The boy replies “I got laid!” At which point, his mother flies into a rage. She grabs her son by the ear, drags him into the living room to where the boys’ father is reading the paper. “You tell your father what you did in school today!” She shouts, to which the boy replies “I got laid!” his father looks cross, and asks the boy’s mother to leave the room while he has a talk with their son.
After the mother is gone, the father’s expression changes to one of pride and elation. “Atta boy!” he tells his son. “Your mother wouldn’t understand, but i’m proud of you! You’re a man now and you should go get all the tail you can chase down!” The son smiles, thanks his dad, and goes on his merry way.
The next day, the father sees his son coming home from school. “So,” he whispers conspiratorially in his sons’ ear “did you get laid again today?” The son looks at his father and says “Oh no, I couldn’t. My ass still hurts from yesterday!”
A woman walks into a bar with a duck under each arm. The bartender says, “Hey you! Youcan’t bring that pig in here!”
The woman replies, “They’re ducks!” The bartender says, “Yeah, I know. I was talking to them.”
A man is driving around in a pickup truck full of penguins. A cop pulls him over and yells at him, “Hey! You can’t just drive these penguins around town! Take them to the zoo right now!”
The next day, the cop sees the same pickup truck full of penguins drive by, only this time all the penguins are wearing sunglasses. The cop pulls the truck over and yells at the driver, “I thought I told you to take these penguins to the zoo!”
“I did that yesterday.” says the driver “Today we’re going to the beach.”
Just to give a third option on the panda joke the way I always heard it was(condensed version since it has been given twice)
The panda picks up two prostitutes, gives them oral, pulls out a gun, shoots one of the women, and tells the other one to look it up, as he walks out of room.
Panda, noun, A furry mammal that eats bushes, shoots, and leaves.
What’s green, red, and going 50 MPH in a tight circle?
Some frogs in a blender.
What’s brown and lies on a piano bench?
Beethoven’s Last Movement.
What’s the definition of perfect pitch in a piccolo?
When you throw it in the toilet and don’t hit the rim.
John Tesh’s musical career.
Three men show up at the pearly gates. St. Peter turns to the first man and asks him how he died. “Well St. Peter, it’s like this. I lived in this high-rise apartment. I came home early from work one day to surprise my wife. When I got there, I found her sitting on our bed wearing sexy lingerie. I asked her what she was doing, and she said she knew I was coming home early, so she was dressed like that for me. I know she couldn’t have known I was coming home early, and figured another man must be in our apartment. I looked under the bed, in the closet, but found nothing. Then, suddenly I spotted some fingers hanging on to the balcony ledge outside our bedroom. I walked over and stomped on those fingers. This guy fell quite a ways, but landed in the swimming pool, swam to the side, got out and began walking away. Well, by this time I was so enraged I grabbed the heaviest thing I could find… the refrigerator. I dragged it to the balcony, threw it over, and squashed him. I was later arrested and sentenced to death, and that’s how I got here.”
“Wow, what a story” exclaimed St. Peter. Then he turned to the second guy and asked how he had died.
"Well, it’s like this. I lived in this high-rise apartment. I lifted weights a lot, and one day I was lifting my weights over my head. They were very heavy, and I lost my balance and stumbled backwards, falling over my balcony. I thought I was dead for sure, but I caught the balcony right below mine with my fingertips. As I was trying to figure out how I was going to get someone’s attention to help me back up, some asshole stomped on my fingers. I fell way down, but ended up landing in the pool. I swam to the side and got out. I gave thanks that I had cheated death twice that day, and was walking away when someone dropped a fridge on me, killing me instantly.
“Oh my, that’s one of the worst stories I’ve ever heard” said St. Peter. Then he turned to the third guy and asked him how he died.
"Ok, St. Peter. You’re never going to believe this, but there I was, minding my own business, buck naked in this fridge… 
A little girl walks up to her mother and asks her a question. “Mommy,” the girl says “Suzie from across the street told me that a baby comes out of a woman where a man…sticks his thing in. Is that true?”
The mother, a conservative and uptight woman is uncomfortable discussing this. But decides that at least her daughter has found out about this matter and she won’t have to explain it. “Yes, Suzie is right. A baby comes out of a woman where the man…sticks his thing in.”
The daughter thinks about this for a while. Then asks her mother: “when I grow up and I have a baby, and the baby comes out of “there” – well, won’t it knock out all my teeth?”
Another one that’s better when spoken:
Three strings walk into a bar. The first one goes up to the bartender and says, “Gimme a drink.” The bartender says, “I’m sorry sir, we don’t serve strings here.” The second string thinks that maybe if he’s a bit more polite then the bartender will give him a drink. “Excuse me, but if it isn’t too much trouble, could I please have a drink?” he said. The bartender says, “Look, we don’t serve strings here, so get out!” The third string has an idea. He goes into the bathroom, bends himself into a loop and messes up his hair. He comes out says, “Could I have a drink?” The bartender says, “Aren’t you a string?” The string says, “Nope, I’m afraid not!”
I love that joke. If you don’t get it, say the last line out loud (remember, it’s better as a spoken joke, rather than written). If you still don’t get it, post and I’m sure someone (or me) will clarify. Oh, and I also like the one about Descartes.
My favorite…
Thor is sitting all by his lonesome in Valhalla and he gets a hankerin’ for some mortal flesh.
He pops on down to a singles bar (this happened in the late '70’s it seems) and he sees a hot looking lady at the end of the bar. Their eyes meet and he strolls up to her side. No words are spoken…, she just takes him by the hand and whisks him off to her place.
They then proceed to make “one night stand” history. Three days later they have been going at it non-stop, when she finally gets up and goes into the bathroom.
So, Thor is feeling pretty pleased with himself and admiring his god-like stamina, when he realizes that this woman must think this is all pretty unusual. He’s thinking that, hey, he’s a stand up kinda guy…, he should just tell her straight out that she is making it with an immortal being.
After a few minutes she walks back into the room and he looks knowingly at her and says, nonchalantly, “You know, I’m actually Thor…”.
She rolls her eyes and says, “You’re thore…!, I’m tho thore I can barely pith!!”
This one could be based on a true story.
During an awards ceremony at N.D. High School, the principal Mr. Ben announces that the Math awards will be given out by Mr. Kevin, the Calculus teacher.
Mr. Kevin stands up in front of the assembled students and presents the awards. After the final award is presented, one of the students in the “senior” section says, “Calculus teacher’s a sonofabitch.”
Mr. Ben stands up and says, “I am truly appalled that one of our own bright students at N.D. High would utter such a horrible phrase. I would like the person who called our Calculus teacher a sonofabitch to stand up.”
No one stands.
Mr. Ben shakes his head. “I would like the person who is sitting beside the person who called the Calculus teacher a sonofabitch to please stand up.”
No one stands.
Mr. Ben says, “I can’t believe this. I will not have people leaving this ceremony believing that this is typical behavior for N.D. High School students. Now I would like for the person who is sitting beside the person who is sitting beside the person who called our Calculus teacher a sonofabitch to please stand up.”
No one stands.
Finally, a student in the “senior” section rises. “Mr. Ben,” the student begins, “I am not the student who called your Calculus teacher a sonofabitch.” The student continues, “Mr. Ben, I’m not the student who is sitting beside the student who called your Calculus teacher a sonofabitch. Mr. Ben, I’m not even the student who’s sitting beside the student who’s sitting beside the student who called your Calculus teacher a sonofabitch.”
“Mr. Ben, what I want to know is…who called that sonofabitch a Calculus teacher?”