Mondegreen: "Bikini Sports Ponchin" is frequently Mondegreen'ed to variations on "Lickin' His Balls, Ball-Chin".
From Koi No Mega Lover: "BITCH, YOU ROCK! GET UP! GET YOUR WAY!"
"Sweet 'n' sour, Pikachu bacon lover!"
Despite what the Death Note fansubs would have you think, they are not singing "Hey, hey, ningen SUCKER! Ah ningen ningen FUCKER!" in "What's Up People?"
The entirety of "What's Up People?" is mondegreen-rich material. Go into any video of the song on YouTube and check the comments, and chances are you'll find commenters making fun of the lyrics. Heck, many Buffalaxes of the videos (both the MV and the Death Note OP) have been made.
True Art: The video for "Zetsubou Billy" strongly implies that Kira took out all the 'fake' bands, leaving Maximum the Hormone, presumably for the reason they are True Music.