This one is a classic and so apropos in the context of my recent math rant.
Two mathematicians were having dinner in a restaurant, arguing about the average mathematical knowledge of the American public. One mathematician claimed that this average was woefully inadequate, the other maintained that it was surprisingly high.
"I'll tell you what," said the cynic. "Ask that waitress a simple math question. If she gets it right, I'll pick up dinner. If not, you buy." He then excused himself to visit the men's room.
The other called the waitress over. "When my friend returns," he told her, "I'm going to ask you a question and I want you to respond 'one-third x cubed.' There's twenty bucks in it for you." She agreed.
The cynic returned from the bathroom and the plotting mathematician called the waitress over. "The food was wonderful, thank you! Incidentally, do you know what the integral of x squared is?"
The waitress looked pensive, almost pained. She looked around the room, at her feet, made gurgling noises, and finally said, "Um, one-third x cubed?"
Chagrined, the cynic paid the check. The waitress turned, walked a few paces away, and muttered under her breath, "...plus a constant."
If that ain't a knee-slapper... well then, you're probably a Three Stooges fan.
Three statisticians go hunting. They see a rabbit and the first one shoots, missing it on the left. The second one shoots and misses it on the right. The third one shouts: "We've hit it!"