Continuity mistake: During the scene at Gitmo while they are having lunch, the opening camera shot shows Col. Jessup and Lt. Kendrick sitting beside each other, almost touching shoulders. But in the next shot from behind Jessup, there is about a 2 or 3 foot space on his left side.
Continuity mistake: When Kaffee drives up to the newsstand at night and buys his magazine and chats with the news vendor, his tie knot is undone down to the second button on his shirt. When he returns to his car and is startled by Markinson in the back seat, his tie is undone only a bit past the first button, much higher than the previous shot. This is largely due, Director Rob Reiner explains, to the fact that part of the scene was shot in D.C. and part of the scene was shot in L.A.
Answer: It's something done to one trooper in a unit who is not pulling his load, to let him know his teammates are tired of him making them look bad. It can range from a beating after lights out to scrubbing a soldier who won't shower with toilet brushes and Comet. (And yes, both of those are from my own military experience, though I wasn't the victim!) It's meant to give a warning and doesn't normally harm anything but the victim's pride. They are strongly against regulations in the past year or two as several soldiers were injured by their unit getting overzealous, just like in the movie.
Grumpy Scot