From the ArcaMax Publishing, Jokes Newsletter:
http://www.arcamax.com/news/jokes/s-418033-650630
My wife was in labor with our first child. Things were going pretty
well when suddenly she began to shout, "Shouldn't, couldn't, wouldn't,
didn't, can't!"
"Doctor, what's wrong with my wife?"
"Nothing. She's just having contractions."