So, yes, there's a Black Sabbath parody band called Mac Sabbath, and they sing about McDonald's.
You can watch a not-quite-pro-shot video of the band performing "Pair-a-Buns" (their version of "Paranoid") below.
"I once burned your meal / My old job was cooking veal / Now it's a culinary crime / All our future is pink slime," the frontman, Ronald Osbourne, sings in "Frying Pan." Feel free to sing along, since the video includes the lyrics.
The band also features creepy costumed versions of Grimace (Grimalice), Hamburglar (Catburglar) and Mayor McCheese (Slayer McCheese).
If you like this sorta thing, follow Mac Sabbath on Facebook.