The act of intercourse that is had when someone bends their leg and spreads the skin in the shape of a butt and the penis is thrust in and out of that shape.
Popping in through a door or into an office cubicle so fast that the occupant therein never hears you coming and loses bodily fluids (or at least is really startled). Think of how Kramer always entered Jerry's apartment on Seinfeld.
I'm so tense at work because I never know when my boss is going to come kramering into my cubicle and make me spill coffee all over the keyboard!