Three men—a mathematician, a biologist, and an engineer—are discussing their love lives. The mathematician starts off talking about how much he loves having a wife. She takes care of him. She always there for him. She's so constant, just everything he could want. But the biologist disagrees. "What you really need is a mistress," he says. "My wife is boring, but my mistress always makes sure there's something new and exciting going on." Those two argue back and forth for a little while until, finally, they ask the engineer to break the tie. Which is better, a wife, or a mistress? "I like having both," says the engineer... "That way, one of them always assumes I'm off spending time with the other one, and I can go into the office and get some work done."