John married a woman who had an identical twin, and a year later he was in court filing for divorce. The judge asks John why he wants to have the divorce.

"Well, your honor," John states, "Every once in a while my sister-in-law will come over to visit, and they look so similar I have accidently made love to her."

"Surely there must be some difference between your wife and her sister." The judge said.

"You'd better believe it! That's why I want the divorce!"