If brains were taxed, Slade would get a rebate.
Slade's Tax Rebate
Explanation
Explain Bear
Alright listen up, nimrod. The joke is that Slade ain't got no brains. So if the guv'mint tried to tax brains, Slade would actually get money back. It's funny 'cause it's true, and you probably wouldn't get a rebate either, smoothbrain.