Two guard stories:
First one - I was flying around Central CA a couple years ago, enroute to SFO. A student pilot was transmitting on guard, lost and with a dying electrical system. Dumbass guard nazi pipes in with "Yer on Guard!" I tell dumbass to shut his yap (politely), and I was able to get the student back in touch with a local approach controller.
Second story - The one and only time I was flying with a guard nazi... The real deal, with itchy trigger finger just HOVERING over the PTT, at the ready to tear into all who dared transmit an errant in range call. I'm flying, and we get within range of our destination. Defender of the airwaves says he's off to ops (we're both monitoring 121.5 on #2), and proceeds to make an unusually long winded call to ops - without actually switching to ops. Yep, his wordy spiel was TX on guard. Karma, so rarely known in my presence, came through beautifully as every guard nazi on the west coast blasted this guy. I was laughing my ass off, while he desperately fumbled the RTU to make the lashings stop. It was awesome.