The object shown is known as a tire "cheetah". It's charged with air up to around 120-150 PSI (depending on which one you get), and the handle releases it all at once. It has a hook on the end of the nozzle that you place on the rim of a wheel that you're putting a tire on, but cannot seat due to the beads on the tire collapsing too far together, usually due to improper tire storage. Basically, a huge rush of air goes into the tire and pushes the tire beads out against the rim seats, while leaving enough pressure inside the tire to keep it there while you properly seat it.
It's a machine of pure destruction in the hands of co-workers, especially when there's a lot of snow or paper-work around.
Thing is you could actually kill someone doing something like this if you're not careful. Put a blast of air in the right spot, it'll just rupture everything inside of you, more or less.