This is how you put letters or words that are not aloud in your clan.
1 Go on mw2 and edit your clan tag.
2 Type in a word that is not aloud but dont hit enter.
3 So once you have that word turn off your modem or router.
4 Now once you turned off your modem or rouder click enter.
5 It should sign you out.
6 Sign back in and go to multi-player and you will have it.
How to put IW into your clan tag.
Go to edit clan tag and put I W
Then it will say "you are not allowed to use the IW clan tag"
Go back and change it to IW then it should work.