For the last girl friend I had before meeting my wife, all it took was being conscious! (And even THAT was only conditionally necessary. Most of the time, when we fucked, she wanted me to keep fucking her until she came so hard that she passed out. This happened quite often, BTW. In addition to that, she wanted to feel me thrusting inside her when she slowly regained consciousness. It was absolute heaven for a 19-year old, but it played hell with my college grades!)