Facebump
When a guy gets his face smacked by a girl's butt while he's on his knees. It’s usually before she sits on his face or when she's feeling extra cruel.
He was on his knees and got a face bump from his boss before she sat on his face during the meeting.
She bumped his face with her butt before she gave him a face sit in the gym.
He got a face bump from his girlfriend right before she sat on his face during a workout.