At a sex liberation convention an expert on sexual problems addressed his audience: "A good sexual life is very good; you prevent a lot of stress in having regular sex. Normally two or three times a week will do. Who of you does have a healthy sex life ?"

80 or so people raised their hands. "And how many do have sex once a month ?"

Maybe 10 hands were raised. "And is there somebody who has less sex ?"

A fine young man stood up and waved his hand. "Me, sir", he smiled, "I have sex once a year." "ONCE A YEAR ??"

The expert exclaimed. "But why are you so happy ?"

"Tonight's the night..."