the process of doing someone doggy style in front of a window while a friend hides somewhere in the room. Sometime in the middle of fucking, the man that's fucking his trick pulls out and lets his buddy in without the hoe knowing. He runs around to the other side of the window, yells "Surprise!", and sees how long his buddy can "ride the bull".
My best friend Joe had the hots for my woman so I let him ride the bull.