Plato and a Platypus Walk into a Bar

There's a book out there that teaches philosophical concepts through telling jokes.

Though some of the jokes are pretty heavy and pretty inappropriate, they are quite funny. They would also serve to be great ice breakers should the need arise.

Here's an example:
Some tourists at the Museum of Natural History are marveling at the dinosaur bones. One of them asks the guard, "Can you tell me how old these bones are?"
The guard replies, "They're three million, four years and six months old."
"That's an awfully exact number," says the tourist. "How do you know their age so precisely?"
The guard answers, "Well, the dinosaur bones were three million years old when I started working here, and that was four and a half years ago."

It may not be the best use of teacher's choice money (aside from the clear error in geologic time), but I suppose some of these are pretty funny. They could get a classroom in line or you can use these as sorts of incentives for good class behavior.