CALF ON A CLIFF
When you are nailing a girl from behind and you drive her to the edge of the bed. This forces her to reel her arms in a reverse direction in an attempt to keep herself on the bed so as to not interupt the nailing and fall on her face.
"I was pullin a calf on a cliff last night but that bitch fell on her face and broke her nose which led to coitus interuptus."