Reminds me on the old Commodore 64 Quantum-Link service (former version of AOL), there was a hack called 'Q-Armor' where you could get a username of all spaces, and no sysops or any chat room managers could kick you, or do anything to your account.
This only worked if 'obar' or 'oobar' was unregistered, but it was a pretty nifty way to steal single word usernames, and speaks to some strange validation/truncation somewhere in the code.