If you were ever dumb enough to lose your beret before forming up, you'll know all about this. You'd be that one guy. If you haven't you'll have more than likely seen it at some point.
You simply can't go on parade without your beret on. Those that have lost it, and have their helmet nearby, would have to put their helmet on. It makes sense. However, if you were that unlucky fellow wearing your helmet, while everyone else was wearing the correct head dress, you'd stick out like a sore thumb. Everyone else would know that you'd messed up and so would the senior NCOs and Officers.
Thankfully, I never have. It still makes me giggle when I pass a formed up group of soldiers and see it.
