Not quite a car whack-off story, but I swear: 2003-ish some kid in my middle school threw his jacket over him in the last 5-10 mins of downtime our teacher would sometimes give us at the end of class & went to town whilst sitting leaned back in his desk. I only witnessed it once, but a few other students seen him do it before in other classes. No one noticed it at first, then it silently spread like wildfire and kind of elicited more laughs than shock/disgust. No one dared to confront him, not even the teacher. It wasn't consistent hand motion, it was more like slower sporadic bursts every 5 seconds punching through his jacket. It was obvious, but it still made u do a double take.
In his defense, I sat next to him earlier that year (before I knew of his class time guilty pleasure) & he was an alright dude. He wore steel toe boots.