Guybrush is Ben McKenzie, actor, improviser, comedian and science communicator from Melbourne, Australia. He stumbled on this wiki while in preparation for BirdHouse, a charity night of TMBG covers as part of the Comedy @ Trades program in the 2007 Melbourne International Comedy Festival. (He'll be performing Why Does The Sun Shine? (The Sun Is A Mass Of Incandescent Gas) in the guise of his alter-ego, the Man in the Lab Coat.)
Ben loves an awful lot of TMBG songs, and also wikis, being a major contributor to the much nerdier White Wolf Wiki, all about roleplaying games.