68?

A very tired husband came home from the office after a long grueling day to find his wife in her sexiest nightgown waiting for him at the door with a couple of glasses of wine in hand.She took his briefcase from him and led him over to the couch where she proceeded to help make him “more comfortable.””How should we do it tonight, honey?” she cooed in his ear, “Shall we do 69?””I don’t think so dear. I’m pretty tired. How about 68?” he said.”Huh, 68? What’s 68?” she asked, a little puzzled.”You do me, and I’ll owe you one.”