well here's your answer: 21 calories

Yup. That's it. Well lets just quit THAT, then.

http://news.yahoo.com/blogs/sideshow/sex-only-burns-21-calories-according-university-study-224521651.html

However, CBS News notes that some fellow experts question the motivations behind the study, noting that some of the participants received funding from sources including Coca-Cola, the McDonald’s Global Advisory Council and two obesity drug manufacturers—Vivus and Arena Pharmaceuticals.

Do you bust if you got over 21?

I think you get busted if they're under 17