Two elderly gentlemen were visiting.  "I guess you're never too old," the first one boasted.  "Why just yesterday a pretty college girl said she'd be interested in dating me.  But to be perfectly honest, I don't quite understand it."

"Well," said his friend, "you have to remember that nowadays women are more aggressive.  They don't mind being the one to ask."

"No, I don't think it's that."

"Well, maybe you remind her of her father."

"No, it's not that either.  It's just that she also mentioned something about carbon 14."