As much as I love crazy sex, the sight/sound of another cute girl a few feet away getting the same treatment (or worse!) always makes it 100x hotter. This is why I like swingers clubs... (x-post /r/gangbang)
Every girl deserves to experience this at least once. If you've never had all your holes filled at the same time (by actual cocks), you haven't had good sex. (In my opinion.)