Many moons ago when I was at school we had a visit for a few days from some RM PT instructors doing the usual recruitment stuff. As part of it they ran a self defence class at lunchtime and one day I made the mistake of not checking which t shirt I'd grabbed out of the drawer in the morning. It was a marron one with a parachute reg badge on it and, despite my best efforts to hide at the back of the class, it was spotted and I was "volunteered" for all the demos