The resulting dark colored stain around a penis when aggressive doggy-style thrusting results in accidental anal penetration. AKA The Stefanelli
"Dude I had the biggest slip up last night. We were absolutely wasted last night and going at it like rabid monkeys when I pulled out too far and ended up accidentally doing anal. Then I looked down and there was this brown stain around my cock...WTF?"
"HA...sounds like you got your first Rogue Doughnut. I'm gonna start calling you stefanelli from now on."