I have a fraternity brother like that. Little tiny guy. Doesn't look like a threat to anyone.

He was a many-black-belt instructor for one of the flavor of 'itsu" martial arts. He was the guy that would train law enforcement officers what to do if someone reached over and grabbed their badge. I recommend you don't reach for ANYTHING on an officer.

He'd make us put a hard boiled egg on our head and do a round-house jumping kick where his leg/foot would be up higher than your head, sweep across, and he'd kick the egg off of your head without hurting or killing you.

He'd do the same kick across your nose where his foot was missing you by a 1/4 inch.

He was so damn lightening fast with his punches, kicks, etc, that you'd never know what killed you.

We used to let him have "Door Duty" at parties.

Nice guy, but I'm sure he could literally instantly kill anyone with his hands/feet, who pissed him off, or directly threatened him or his friends.