When a man's penis enters his own butthole. This most often occurs by accident during an extreme sex act but has also been performed solo, hands free, by a very talented few.
When your driving and you don't know where you're going, and you miss the exit, and instead of saying u-turn you say you have to make a loop de loop. You say this so ease the pain of realizing you actually have to turn around. It sounds less harsh than having to take a u-turn.