A real rib tickler is to twat the RSM's car bumper with a baseball bat. With the technology about today the bumper will spring back into shape with no damage but you'll trigger off the airbag on the steering wheel. Shit's and giggles all round. He'll love it.
The old classic, send a red arse/sprog/crowbag or whatever you want to call them into see the badge carrying an item of equipment of your choosing, (I heard a chainsaw is best) any piece of CES kit will do though, wrecking bar, bike chain, D shackle that kind of shit, tell crow to deliver sealed envelope to RSM. Inside envelope it says Good morning RSM my name is Private....crowbag.....promote me now or I'll smash up cut up destroy your office with this chainsaw, wrecking bar, bike chain etc etc........classic. If he doesn't see the funny side he's a cunt...then again My old RSM demoted the reggie mascot for scoffing the flowers outside BHQ and put a bike in jail for slouching against a wall outside the med centre.....mad cunt.
If your regiment has a mascot such as a goat, who is probably a corporal, arrange to promote the goat to the rank of RSM. Send a letter or a Signal to the RSM informing him that he has got to find space in his office to share with the newly promoted regimental mascot.
stretch a condom over his cars exhaust pipe, when he drives off, he is followed by a six foot long balloon.
Jack up the back of his car, rest it down on bricks so the back wheels are about 6mm off the ground. when he tries to drive off, the back wheels spin like fcuk and he stays in the same place.