I'm Facetious!
You know what really grinds my gears?
Two things:
1) Arrogant young teenagers on XBOX Live.
2) Annoying (and arrogant) middle-aged folks on XBOX Live.
Some of the most agitating (and some of the best, too) gamers are on XBOX Live. Which really kind of ruins the whole experience of being able to VOIP with your team in games like Halo 2. I'm a big proponent of "shut up and play your own game". It's one thing to mess with your friends, but its another when you're messing with some unknown entity.
So my advice is shut up and play the game.
Unless you're making a constructive comment to your teammates or chatting with friends, you don't need to be using the headset.
And no, you are not a good singer. Gears of War isn't the place for a bad karaoke. Halo 2 isn't the place for you to sing some horribly annoying Usher song.
Shut up and play the game.
Because I'm too lazy to mute you. :P