The following is said to be the most politically incorrect joke of all time

A sadist, a masochist, a murderer, a necrophiliac, a zoophiliac and a pyromaniac are all sitting on a bench in a mental institution.

"Let's have sex with a cat?" asked the zoophiliac.

"Let's have sex with the cat and then torture it?" says the sadist.

"Let's have sex with the cat, torture it and then kill it?" shouted the murderer.

"Let's have sex with the cat, torture it, kill it and then have sex with it again?" said the necrophiliac.

"Let's have sex with the cat, torture it, kill it, have sex with it again and then burn it?" said the pyromaniac.

There was silence, and then the masochist said: "Meow."