I don't know why, but these things just get on my nerves sometimes :)  Maybe this will turn into a top 10 or top 50...

1. 2 seconds into the game you hear, “What game are we playing"? As if the description in the pre-game lobby and the guy with the deep voice saying "Capture the Flag" aren't enough.
2. "Did I kill you"? You should easily be able to tell whether you killed someone by a) seeing if they're still standing and b) reading the message on your screen that says "You killed <playername>".
3. "Who killed me"? Again, you can easily find this out by reading the message on your screen that says "<playername> killed you".

Feel free to add your own.