Nightwish is an easy choice. That video is old as hell, but still hilarious.
Wishmaster - The Misheard LyricsThe funny thing about this song is that even if you do know the actual lyrics, you still have no idea what the hell the song is about. Unless of course you read Lord of the Rings and Dragonlance and other fantasy series i guess.
Misheard Lyrics: Crownless