the combination of hormones, proteins, and other bodily chemicals (seratonin, epinephrine, etc.) that make sex a physically pleasurable act.
the reason people like sex is because if we didn't, the human race would die out from sexual apathy. sexahol is the biological reason why we don't.
I've got a huge term paper due, but I haven't got my sexahol fix in a while, so I"m hitting the clubs.