Very early on, when I first started getting into martial arts, right when i first joined a tkd club, this is in fact exactly what happened.
One of the students in the school got beligerant in a convenience store to a guy who he perceived to have done him some slight in etiquette.
They step outside and the guy from the club I had just joined was being ridiculous and rude while the other guy, who was wearing a freaking cowboy hat, boots and sheepskin jacket proceeds to karate™ my classmate's ass into the ground, the back of his truck, the ground again and so on until intervention took place and we meandered back to the place we were before going to the store.
So, what is the value of a black belt?