"Once a week?" A third of the people raise their hands, smiling a little less.
"Once a month?" Only a few people raise their hands.
Then he asks, "OK, how about once a year?"
One man in the back jumps up and down, waving his hands, seeming very happy. The therapist is shocked - this disproves his theory.
"If you have sex only once a year," he asks, "why are you so happy?"
The man yells, "Today’s the day!"