2 guilds on my server I really like the name of:
Tavern of the Lazy Peon
Raiders of the Lost Orc
I just find them really funny and unique.
The others with the kode, bike, mount, mom, girlfriend and so on is just old.
There is one honorary mention: LAZORZ PEW PEW (maybe pew pew lazorz?)
No not one of the wannabees, but the guild on a RP server that got that name.. got reported.. and had a GM change their name to Sword KLANK KLANK (or something to that effect)... that was funny. (another forced name change was Seal Cub Clubbing, that got changed to Orgrimmar Trashbin Collectors).