An architect, an artist and an engineer were discussing whether it
was better to spend time with the wife or a mistress.

The architect said, "I enjoyed time with my wife, building a solid
foundation for an enduring relationship.

The artist said, "I enjoyed time with my mistress, because of the
passion and mystery I found there."

The engineer said, "I like both."

"Both?" they questioned.

The Engineer said, "Yeah. If you have a wife and a mistress, they will
each assume you are spending time with the other woman, and you can go
to the lab and get some work done."