In the U.S. Air Force, and possibly other lesser military branches, the practice of hitting a recently promoted enlisted member in the arm where his rank is sewn on. As only higher ranking folks get to do the hitting, someone who is promoted from Airman Basic can expect the beating of a lifetime.
It is, admittedly, a lower form of hazing as compared to, say, blood wings, but that's not to say it's not without its cruel charm.