Why aren't fish allowed to play in an orchestra?
Because you can tune a piano, but you can't tune-a-fish.
The biggest and roundest knight at King Arthur's round table was Sir Cumference...
Apparently he acquired his size from too much pi.
Dear Algebra Teacher,
Please stop asking us to find your X!
Interviewer: How do you spell Mississippi?
Dumb Guy: Which one? The river or the state?