Indeed, make an effort to check your mic select - 100% fair point. But come on...
I heard it again today while in Sydney. Some guy goes out on guard inadvertantly - hey, it's going to happen from time to time. He even realised it, and pretty much straight up ceased transmitting, and...
In less than a second someone is on there - "Guard mate". Fair enough to let him know, but surely you realise that he has realised.
But wait, there's more! (Like an annoying telemarketing spray)
Another "121.5 twit" feels the need to pipe up in a stupid voice. Then, after that, yet another... What is going through the space between
this guy's ears, when after two "guard police" transmissions, he feels the need to add a third?!!
I can see it now, he's sitting there, with PTT in one hand and d1k in the other, feeling smug and superior but vowing to be faster on the draw next time, so as to get in first - with a new, improved and even sillier voice or sound effect.
Some good points made here about radio use, but the question in the thread's title remains unanswered...