Sex

http://www.prevention.com/sex/better-sex/how-many-calories-does-sex-burn

"Men burn 100 calories in the average sheets session, while women expend 69. The typical romp lasts 25 minutes from the start of foreplay to the end of the deed, but that's just an average—the times varied widely in the study, and ranged between 10 and 57 minutes. The longer the session, the more calories burned."

That's your baseline, I guess.