Heh, heh, heh.
A rifle powered by hot air?? He'll never run out of propellant!
Did the counter person match the rifle to the owner's personality?
If you got your own air soft gun, whenever he misbehaved, you could just shoot him in the butt, kinda like spraying a cat with water to train them.
........
..........that's all I can come up with right now.