Several things for you to remember:
* You can't change the username of ... once you set it.
* You can't transfer the ownership of a username to another party.
* You can't violate anyone else's trademark rights.
* If you are acquiring a username to sell it in the future (squatting), you will lose it.
* Usernames may be reclaimed for other unauthorised usages.
Are you sure you want to set ... as ...'s username?