A sexual position where you lay on your back with the girl penetrated on your chest. You then spin her around like a helicopter. I suppose you can do it in a variety of ways but you get the basic idea.
Performing the act of copulation while the Male continuously spins his partner around the axis of his penis and makes helicopter (aka. machine gun) noises.
"I prefer peforming a sex-copter over a donkey punch anyday." - anonymous