Except for the shortform of my first name, somefriends called me "Wolfie" because i once i had an awesome beard combined with a wild (but well-kept) mane.
They said i look like a werewolf.
Also when i started playin' soccer i got the nickname "Tiger" on the local sport field. The old trainer who still remember me (~17 years later), still call me Tiger when they see me today.
Ah jeah.. and i got the nickname BUY in my local MTG Friday Night Magic Event.. because we've a bunch of pros in our region and it's pretty tough to win a match

(For those, who don't know what BUY means, that's a free win at a tournament, which usually is handed out to the lowest player, if the number of players is uneven.)