An Apple computer walks into a bar.
Bartender says, “What’ll it be, Mac?”
What plays guitar and kills critters?
Dweezil Zappa
Once upon a time there was a very large office building in a very large city. This building had 30 levels: level 1, level 2, level 3, level 4, level 5, level 6, level 7, level 8, level 9, level 10, level 11, level 12, level 13, level 14, level 15, level 16, level 17, level 18, level 19, level 20, level 21, level 22, level 23, level 24, level 25, level 26, level 27, level 28, level 29, and level 30.
One day the owner of the building decided to get a PA system installed on every level, in case there was ever a fire and everyone in the building needed to be contacted at once. The system was installed on every level: level 1, level 2, level 3, level 4, level 5, level 6, level 7, level 8, level 9, level 10, level 11, level 12, level 13, level 14, level 15, level 16, level 17, level 18, level 19, level 20, level 21, level 22, level 23, level 24, level 25, level 26, level 27, level 28, level 29, and level 30.
One day, an employee named John was doing some paperwork on the 21st level when he saw the pager for the PA system in his boss’s office. He could not resist. He picked up the pager, turned it on, cleared his throat, and told a joke. It was funniest joke anyone in the building had ever heard. They were rolling in the aisles, laughing their heads off. The accountants on level 3 were in tears. The engineers on level 24 were in hysterics. In fact, workers on every level – level 1, level 2, level 3, level 4, level 5, level 6, level 7, level 8, level 9, level 10, level 11, level 12, level 13, level 14, level 15, level 16, level 17, level 18, level 19, level 20, level 21, level 22, level 23, level 24, level 25, level 26, level 27, level 28, level 29, and level 30 – could not stop laughing.
John walked out the door of his boss’s office, feeling all proud of himself, when who should he run into but his boss. “John, come with me now!” John relunctantly followed his boss back into his office. His boss looked at him with fury in his eyes. “John,” he said, “your joke was very disruptive to the workers in this building! Productivity was decreased on level 1, level 2, level 3, level 4, level 5, level 6, level 7, level 8, level 9, level 10, level 11, level 12, level 13, level 14, level 15, level 16, level 17, level 18, level 19, level 20, level 21, level 22, level 23, level 24, level 25, level 26, level 27, level 28, level 29, and level 30! You’re fired! Clean out your desk and get out!”
But then his frown softened and he added, "Still, I have to admit…
…that joke was funny on so many levels."
Two guys walked into a bar. The third guy ducked.
And EmilyG, there is just no good enough punishment for that. 
First grader Johnny is staring out the window. Teacher asks “Johnny, what are you looking at?” “Boids”, says Johnny. “They’re not ‘boids’, they’re 'birds.” “Well”, says Johnny, “they choips like boids.”
How many hipsters does it take to change a lightbulb?
Some obscure number, you’ve probably never heard of it.
How did the hipster burn his tongue?
He ate the pizza before it was cool.
I was standing in the park the other day, wondering why a frisbee appears larger the closer it gets. And then it hit me.
There are 10 kinds of people in the world: those who understand binary and those who don’t.
(An odd kind of joke that only works when written, and not when spoken.)
Once upon a time there was a Snail.
This Snail spent his time sitting on a curb by the side of a road, in front of an auto dealership, watching all the car passing by. The Snail’s fantasy was to own a fast car like that, so he could go around that fast too.
So the little Snail saved up money for many years, until he could afford his own car. Then he went into the dealership and bought one.
Now this was some years ago, when expensive high-powered “Z” cars were all the fad. The car he bought actually had a “Z” painted on the doors, which many brands did in those days. But this Snail insisted that the dealership paint over the letter “Z” with a big “S” (for Snail, of course), and the car salesman agreed to this.
So the Snail got his car. He climbed into the driver’s seat and leaped off the seat onto the accelerator pedal, flooring it, and the car tore out of the dealership and down the street, leaving only tire tracks and dust behind, and it was gone out of sight!
The salesman watched the car lay rubber off into the distance, with his jaw agape, and he exclaimed: “Wow! Look at that S car go!”
A very dated joke:
Did you hear about the movie about a friendly bear who wants to go to school to become a rabbi? It’s called Yentl Ben.
How do you get a CENSORED to CENSORED a CENSORED?
CENSORED her CENSORED with CENSORED.
Have you heard the joke about the three holes in the ground?
No?
Well, well, well!
I don’t get it. 
My favorite knock-knock joke goes like this:
YOU: “Say, I’ve got an amazing knock-knock joke, but I need you to start.”
UNSUSPECTING VICTIM: “Okay, knock knock.”
Y: “Who’s there?”
V: “…”
There is subsequently a pronounced phatic hiatus. Try it, you’d be surprised how often it works. 
I’ve posted this before.
Chris went into the local restaurant every day at precisely twelve and invariably ordered the same thing, a large bowl of the soup of the day. This had gone on for so many years that Chris and the waitstaff knew each other by their first names, and every noon, as Chris sat down–always at the same table–one of the waitstaff would deftly serve a large bowl of piping hot soup to Chris, who immediately would begin to eat it.
Today was no different. Chris entered, sat down, and Pat served the soup and walked away. A minute or two later, Pat saw that Chris was just sitting, staring at the soup.
Pat went over to Chris and said, “What’s the matter, Chris? Is there something wrong with the soup?”
Chris grumbled, “Taste it.”
Pat said, “I don’t have to taste it. Just tell me. Is it too hot? I’ll fan it. Too cold? I’ll get you some fresh. Does it need salt? Pepper? I’ll fix it.”
Chris said, a little louder, “Taste it, I tell you!”
Pat said, “All right. All right. Don’t get mad. I’ll taste it. Hmm–now where’s the spoon?”
And Chris said, “A-HAAAA!”
Did you hear the one about the constipated mathematician?
He worked it out with a pencil.
Why is six afraid of seven?
Because seven eight nine…
what did the leper say to the hooker?
“keep the tip”
Yeah, I like Coming to America too. Better with the faux heavy Yiddish accent: “ACHHHH-HAAAGGGHH!”
If you don’t know hexadecimal, then fifteen you!
Heisenberg and Schrödinger are speeding down the highway when a cop pulls them over. The officer says to Heisenberg, “Do you know how fast you were going?” Heisenberg answers “No idea, but I can tell you exactly where I was!”
The officer decides this odd response is grounds to search the vehicle. He looks in the trunk and cries out, “Do you guys know there’s a dead cat in here?!” Schrödinger replies, “Well, I do now!”