In-Jokes

An "in-joke" is one which three or fewer people understand, and forms the bedrock of Encyclopedia Dramatica.

For example, an ordinary joke might be as follows;

Q. Why did the chicken cross the road?
A. To get to the other side

whereas an in-joke might be;

Q. Why did the chicken cross the road?
A. Because of a point mutation in the gene coding for its sinal magnetite receptor.

Other types of joke

In-jokes can be distinguished from unfunny jokes (see GET OUT) or surreal jokes ...

Q. What's black and white and red all over?
A. A gooseberry in a lift.

Q. A horse walks into a bar what does the bartender say? A. Why the long face.

... in that at least other other person, possibly in a covert organisation or a cult, gets the joke and then laughs at it.

(1) PC users
Q. Why did the penguin cross the road?
A. Because it was the Linux corporate logo.

(2) KKK
Q. Why did the black bird cross the road?
A. Because it saw a white woman.