Inoffensive jokes

What are the best "clean" jokes you know, even if they're a little corny and nerdy? Clean as in not involving sex, drugs, guns, dead, foul language, dead babies, pedophilia, etc.

Here's mine:

Q: What's 5 x 4 x 3 x 2 x 1?
A: Five! (5!)

Post 'em.

Well an Englishman, a Scotsman and an Irishman walk into a bar together and order a drink. The drinks they got were not acceptable and the behaviour of the other members of the bar (and in some cases even the bar tender) were rude, annoying and insulted the men. They decided to leave the bar and go and report the incident to ther proper authorities and let them take a course of disiplinary action. Harassment is not acceptable anywhere!