Harold wakes up out of a deep sleep and, feeling
amorous, nudges his wife awake and asks, "Why 
don't we get it on, eh?" She replies, "I have an
appointment at the gynecologist tomorrow and you
know I don't like to make love the night before."
"Alright", he said, and he rolled back over and 
started to go back to sleep. 

A few minutes later, he nudges his wife again and
asks, "You don't by any chance have a dentist's 
appointment tomorrow, do you?"