This is the world's largest air cannon which was made in cooperation with Czech TV show Wonders of Nature. There's definitely a missed opportunity to use it directly on a person. What's the worst that could happen? They fall over? Also they're clearly going by size and not force, because I would beat this thing any day of the week after having some Taco Bell.
Keep going for the full video of them basically just knocking over a bunch of cardboard boxes with this thing. 5:30 is the closest they get to actually hitting anybody with it, but nobody gets seriously injured so it's not entirely satisfying.