Most well-known sex joke?

“Knock Knock”

“Fuck You”

Forget your keys, help me find my car and I’ll drive us both out!
Man: I’d like a little pussy

Prostitute: Me too, mines as big as a hat!

Midget walks up to a prostitute and says, “What would you say to a little fuck?”

The prostitute replies, “How ya doin’, you little fuck?”

I used to work with a conservative older woman who used the expression “your turn in the barrel”, and I always wondered whether she knew where it came from.

I hadn’t heard this one. I found the joke with Google, but don’t understand the premise–how is waving a towel supposed to help?

Are you going for a woosh here?

Just in case you’re not, the point is that the man was bad at pleasing his wife, so when the young stud waved the towel while the mad made love to her, the results were the same as usual. When the young stud made love to her, she reached orgasm, and the man said it was because he was such a good towel waver, even though that had nothing to do with it.

Wrecked him (rectum)? Damn near killed him!

That line I have heard before, but don’t remember the setup. All of these are oldies, but goodies.

You think you’re tired?
I lost the hot dog after the second bar!

… as the bishop said to the actress.

“No, but the guy before you sure was!”

Some variant of this: Little Johnny’s class are talking about what they did on the Fourth of July. When it’s LJ’s turn he tells about how he got hold of this toad and stuck a firecracker up its ass. And the shock teacher corrects him by saying “Rectum!”. Etc.

Boss takes his secretary on a business trip. There’s a mistake at the hotel and they have to share a room. During the night the secretary says “Ooh, Mr Boss, I am so cold, could you please close that window?”
Boss replies, “How would you like to pretend you’re Mrs Boss instead?”
“Oh, yes please Mr Boss!”
“Good, close the window yourself!”

I heard “big as a cat” which makes more sense.

For a fella with two heads, it makes more sense to me the other way, but you’re right, My pussy is as big as a cat does make logical sense.

That’s the one I use, although I say “… as the actress said to the bishop”.

Or the Monty Python “nudge nudge, wink wink” stuff, “he said knowingly”.

That’s not a ring. That’s my wristwatch.

“That’s okay, I’m not really a nun. I’m on my way to a costume party at a gay bar.”
“But, Grandpa! You already paid me for showing you how to put a worm back in its hole.”
“I know, Nigel, but this $5 is from your Grandma.”

“Rubber balls and liquor.” (a young boy’s joke)
“That’s what makes him so mean!”

A young rube goes to a whore house for his first lay. The madame asks him if he knows how to use a condom. He says he doesn’t, so she demonstrates on his thumb how he’s to roll it on.

He goes up and bones the young lady. Afterward, she says “I feel pretty wet inside, did the condom break?”

The boy holds up his thumb and pipes “Nope, good as new!”

“Hey, lady! Your sign fell down!”

Danceswithcats, I remember that punchline (the ending of which I learned as "and a twenty dollar bill for a fucked-up duck) but I can’t remember the joke! Help!

Another plea for help for the set-up for a joke with multiple punchlines, the final one being, “No deer. Run too fast, jump too high.”

Here’s one version. I have heard variations.

Barbara Walters was doing a documentary on the customs of the American Indians. After a tour of the reservation they lived on, she asked why there was a difference in the number of feathers found in the headdresses of the various Indians.

She asked a brave who only had one feather in his headdress what this meant. His reply was “Me have only one squaw, me have only one feather.”

She asked another brave, feeling the first fellow was only joking, this brave had four feathers in his headdress… He replied, “Ugh, me have four feathers because me sleep with four squaws”

Still not convinced the number of feathers indicated the number of squaws involved, she decided to interview the chief.

Now the cheif had a headdress full of feathers which, needless to say, amused Ms. Walters. She asked the chief, “Why do you have so many feathers in your headdress?”

The Chief proudly beat his chest and said, “Me chief, me fuck-em all; big, small, fat, tall, me fuck-em all.” Horrified, Ms. Walters stated, " You should be hung." The chief replied, “You damned right me hung–me hung like buffalo.”

Ms. Walters cried, “You don’t have to be so goddamn hostile.” The chief replied, “Hoss style, dog-style, any style, me fuck-em all.”

Tears in her eyes, Ms. Walters cried, “Oh dear.” The chief replied, “No deer,----me fuck no deer. Run too fast, assholes too high. No fuck deer.”

That’s it, Lurkmeister! (Well, I didn’t hear it with Barbara Walters…)

Thanks!