Anything with random letters and numbers that make no sense:
They think ... no wait, I don't think they were thinking, because when a gamer tag isn't pronounceable, then they invariably get called "hey Dickhead".
There are great gamer tags though... I do love ones that make me laugh. I've been killed by "atoiletseat", "nobody", "daffyduck", "27ninjas" and other nicks that did make me pause and chuckle for a moment. To those that pick annoying gamertags... ok, you win. I was annoyed. In future, I guess the only way for me to win the game is to not get annoyed and to ignore the gamertag.
... dammit, that's hard though... so many annoying people out there. Maybe I'll just give up and change my gamertag to "StonedEliteGrlSniperKilledUwhileDoinUrDaddy".
LOOK WHO CAME: