Q: What's the difference between a monkey and a flea?

A: A monkey can have fleas, but a flea can't have monkeys.

猴子会和跳蚤有什么不同呢?你可能会直接的想到它们俩是一大一小。但除此之外呢，那就是猴子身上可以长跳蚤，而跳蚤身上却不能有猴子。