Cause we shine like the chrome on a Cadillac
You better break a wishbone cause we never wack
Said we're never that and that is that
And we're the nonstop disco powerpack!
Beastie Boys are never wack so you’ll need a lucky break (ie the larger part of a bird’s snapped wishbone) to outdo them. Wishbone is also a type of car suspension. A break in the wishbone of their metaphorical Cadillac is the best you can hope for. Beastie Boys, themselves, would have to fail in order for other MCs to surpass them.
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