You know, I think they should put this in the game, like you can cover your mouth when you're about to yell that. I don't know why, but either my team is deaf or the enemy team has a microphone on me, that when I yell that with all my lungs, only the other team knows I'm fully charged.
Dat Demo indeed... I find that annoying for all classes. When everything is quiet and suddenly you've either made a kill or accidentally called Medic and your class says something that alerts everyone of your presence.
Egh, hate that. Surprisingly, as a Medic the Spies don't get me as much because I'm pretty good and pointing them out. Haven't played Medic in forever, though, so I don't remember what class normally got me.