I have legitimately heard of shaving a beret numerous times over, but always second hand.
I, for one, revel in how perfect this particular new guy anecdote is. A hairy/linty beret quite understandably became The Biggest Thing In The World. Our New Guy searched (as we encourage him to do), and stumbled upon the 'shave your beret' advice. New Guy goes and literally shaves a hole in his beret, which as we all know is actually basically just one big pressed piece of lint that gradually dismantles itself minutes before each and every insepction. Now finding himself with a fingernail sized hole in his beret, and a dumb-yet-relatively-understandable reasont hat his instructors will treat as -the-biggest-deal-ever-in-the-whole-world, New Guy is now in a minor but very justified panic.
Nobody got hurt, no fires were set intentionally or accidentally (yet), nobody was or will be charged, it's Op-Honour compatible, and the only people excluded are Highlanders, which we're used to anyway.
We await at this point just a single conniption fit from a MCpl, one more from a WO, and an exasperated, pained, yet tolerant trip to clothing stores with the Cpl who is the course admin -lackey.
Ah, the sweet innocence of recruits.