Two men are drinking in a bar. One turns to the other and says, “I bet you $100 that I can bite my eye.”
The second fellow thinks to himself, I guess he’s had about enough, so he replies, “OK, show me.”
The first man takes out his glass eye and bites it. So the second man has to pay. A while later the first man says, “I bet you $100 I can bite my other eye.”
The second man thinks, well, he can’t have two glass eyes. He obviously can see. So he says, “All right, show me.”
The first man takes out his false teeth and bites his other eye.