The Old Kawasaki
When a man, is making love to woman, in the doggy style position, with his right hand, he acts as if he's gripping the throttle on a motorcycle handlebar. With each rev of the imaginary throttle, his thumb hooks down, and is inserted into the woman's anus.
"I was taxing this slut from behind, and I slipped her the Old Kawasaki."
"You have to be careful with the Old Kawasaki, sometimes you end up with brown thumb."
"You have to be careful with the Old Kawasaki, sometimes you end up with brown thumb."