A sexual act that requires quite a bit of skill, stealth, and execution.
Start by having seemingly normal intercourse with a partner of your choosing. The lights must be off and you must have a friend, neighbor, or any other willing person hiding in the room. Said accomplice must be willing to masturbate furiously as to build up a quick nut. When you get close to climax, pull out and allow the accomplice to take your place, with you now jacking off in his place. You should both now simultaneously blow your loads, with an immediate quick exit (a window or "going to the bathroom" works).
When she turns on the light and looks around, she will realize that she has been yet another victim of the Cincinnati Creeper. Run quickly from the area, high-fiving your accomplice, and spend the rest of the night telling people, eating beef jerky, and playing Mario Kart.
Hey, anyone wanna go Cincinnati Creepin' tonight? I got some sluts already queued up on Myspace.
That Cincinnati Creeper was perfectly executed. Good shit, man.