A word invented by =WTF= members of the America's Armymultiplayer FPS online game. It is the act of inserting your scrotum into an enemy's mouth after being shot, blown up, thermited, etc... Especially funny when they land in precarious positions, when they are acting like bitches, a noob, or even more funny when they are part of the same clan. Even more funny when you let the receiver of this ungodly act know that you forgot to wipe, forgot to shave or purposely shaved your nuts, or any other variation of scrotum modification.
"LOL, hey Baz I just T bagged that fucking noob Dr. Spray and he enjoyed it, what a homo!"
or
"T-bag, have some borg salted nutz!!"
or
"Check out this noob with his second account, let's TK him and the have a T bag party on his dead body!"
Shallow abbreviation of first name "Tom" or "Thomas". Comic shortening of an already short first name. "T" as in "Mr. T". This, among other now imperceptible ponderings, through transmogrification, equals the capitol "T" mixed with the logical addition of "Bag"; especially when under the influence of tequila, hence, T Bag.
"Don't come running to me for answers as to why we destroyed Mrs. Wilson's tulip garden with the delivery truck....Blame it on Mr. T Bag".