An old woman says to an old man at the retirement home, ""I bet you I can guess your age."" The man doesn't believe her, but tells her to go ahead and try. ""Pull down your pants,"" she says. She inspects his rear end intently for a few minutes and then says, ""You're 84 years old."" ""That's amazing,"" the man says. ""How did you know?"" ""You told me yesterday.""