Lots of marching and shouting goes on on the drill square, and all rather vulgar. Unless some bastard NCO has 'invited' you to do a bit of drill on the square you never walk on it or across it, you always walk around it.
Failure to adhere to this simple rule will result in a screaming monster, which foams at the mouth, sticking you on the end of its Pace Stick and (as if by magic) transporting you to 'The Nick' in a nano second. Nasty, nasty things happen in 'The Nick'. Many go in and few come out.
One punishment for committing terrible crimes, such as having your hands in your pockets, would be to sweep the Drill Square with a toothbrush. The trick here was to use your mate's toothbrush. Or even better - get your mate to do it.