Hands-down the best version of this bit was from Animaniacs...

Gotta love Animaniacs.

Graffiti chalked on the wall outside the London School of Grammar:

All policemen are illegitimate children.

You know it was an autistic immigration official who sunk the Titanic?

What does Lady MacBeth say when she wants to put the dog out for the night?

A guy walks into a bar and the bartender says, "hey, I have a wish in my pocket, it's yours if you want it!"

The guy says "sure!"

The bartender pulls something out of his pocket and hands it to the guy, "now make a wish!"

The guy stands there thinking for a second and says "ok, I wish for 1000 bucks".

A few seconds later, 1000 ducks show up.

The guy looks at the bartender and say "hey what gives, i asked for 1000 bucks and instead i got 1000 ducks."

The bartender looks at the guy and says "yeah, imagine my disappointment when I got a 10 inch pianist."

This one requires a bit of knowledge of the record biz, but I'm sure a numbe of folks on the board will get it:

One day back in August 1977, the president of RCA Records was sitting in his office when one of his assistants walked in:

Assistant: Boss, I have good news and bad news.

Prez: Well, it's been a rough day, so give me the good news first.

A: The good news is we just got word that Elvis Presley died.

P: Wrong. That's not good news. That's great news! We'll re-release all of his old records, have a big publicity campaign and play on the public's sympathy. We'll make more money off the son of a bitch dead than when he was alive! Woo-hoo! OK, so now what's the bad news?

A: The bad news is that Glen Miller's plane just landed and he wants his royalties.

A dog calls 911:

Operator: "911, what is your emergency/"

Dog: "My owner's been gone for two whole seconds!"

Operator: "Wow, that's a real emergency! Is there a couch there you can tear up?"