It's a game hack.  You have to modify certain files on your console using a data transfer cable and your pc, a hex editor and a special program...just search google or youtube for "modern warfare 2 gamertag hack".

Keep in mind, by modifying files on your hard drive (especially for use on the Xbox Live service) could get you banned from Xbox Live.

I saw one that said 'PressAforWeed'

its a harmless mod

surely even if this a 'harmless' mod, the likelyhood is they are trying to cheat in other ways too!
i'm also getting fed up with the 'i'm going to hack your account' bullcrap you hear whenever you beat these idiots!  can anyone clarify whether any of these mods could give these idiots that kind of power, sure i've heard of accounts being hacked before?

lol i seen one a person's name that said "If your Gay Press A"  (the button a at the end)

I think I seen a legit guy with this, a purple name 'Chuck Norris' I clicked on his GT and it said DarkWereWolf with 140, 000 Gamerscore.

Either a Gamerscore hacker, or given that special name from IW.

report them and they get banned... its a hack/mod console and that is against tos.. microsoft bans in 2 days for that and its most of the time permanent ban.. as they see a modded console and it violates all tos..  it bothers me because it takes up half the damn screen, other then that i could care less