Male on top of the Female and once inserted he begins to slowly rotate his body round in a 360' circle whilst thrusting. the woman must lift his legs as they go over her head, and if he hits a good spot the woman is allowed to stop him.
The tricky part is making sure your member doesn't 'pop' out while you're doing this. ... And to keep from laughing. Otherwise its great.
Girl 1: My boyfriend and I tried did the helicopter twirl last night!