I honestly thought the guy was a fraud the first time I saw him.
But there are tons of clips of him online tuning his guitar and playing other songs.
EDIT: Adam just goodrepped me for saying that Muzza's stock went up.
Seriously, though, it has. If the final turns out to be Muzzerer and Muzza beats down Federer, I will be even more grateful.
(I will also gratuitously laugh at MY.)