Dan married one of a pair of identical twin girls. Less than a year later, he was in court filing for a divorce. “OK,” the judge said, “Tell the court why you want a divorce.”

“Well, your Honour,” Dan started, “Every once in a while my sister in law would come over for a visit, and because she and my wife are so identical looking, every once in a while I’d end up making love to her by mistake.”

“Surely there must be some difference between the two women.” the judge said.

“You’d better believe there is a difference, your honor. That’s why I want the divorce.” he replied.