This shirt tells you that the person wearing it is an administrator of the game which means they work on the game and have the ability to block you from playing if they want to. Don't worry admins are usually fair so you wont get blocked as long as you follow the rules otherwise you can count on getting blocked for violation of the rules. (Like speed hacking in the middle of a game) Admins can also be identified in games and chat rooms by their red highlighted names.
Yellow highlighted names = Moderators
Red highlighted names = Admins
Rumor has it that the Admin shirt has up to 200 AP!
It also has 50% absorb bonus making them IMMORTAL!