A have-a-go hero in a restaurant.
Whenever anyone coughs, or clears their throat slightly (no matter how lightly), he would sprint across the restaurant and put that person is a very aggressive/violent Heimlich Maneuver.
No defined dialogue (beyond generic restaurant conversation).
Was thinking of setting this up in a real-time prank video (with a friend as a plant, of course), but would probably have ambulances, police cars and god-knows-what making an unwanted appearance.