"Dean!" Sam does that annoying thing where he looks happy and too insistent and Dean knows he has to say no to some stupid idea. "Did you vote yet?"
Dean doesn't actually say 'what?' but 'what' is written all over his face. And, no, he hasn't voted. And for a good reason, and just for starters, he's dead in several states and probably some small countries, hell the FBI thinks he's dead (sort of, he thinks), he has no really legal drivers license, and he's quite sure that Robert Plant already voted, and, oh, yeah, the next apocalypse, which he sort of feels responsible for. "Vote?" is what he gets out.
"Mid-terms" says Sam. And Dean can tell he's about to get all preachy. "This year we get to choose between Republicrats and Fascists." Sam pauses, Dean thinks that Sam might have thought that Sam was funny. "Always vote Republicrat." says Sam. Sam wasn't funny.
"You look funny." says Dean by way of distraction. Because, he's dead, really, how is he supposed to vote; and he's saved the world one too many time to get all caught up in, well, yeah, he knows what this is, it's a national cluster fuck.
"You won't think its soooo fucking funny when…" Yep, angry preachy face, Sam could have been a televangelist in another life. "global warming….trans-rights…Mexicans…immigrants…Paris accord…Russian interference…children in prison camps…freedom of the press…hate speech…Muslim-ban…wall…did he say wall…sexual assault, wait, no rape…stacked supreme court…troops to the boarder…birth-right citizenship…anti-semitism…white-supremacist…nationalist…" and then Sammy says something that counts: "You killed Hitler the first time, I don't see why you are willing to let him take power now."
Dean votes, not as Robert Plant, that would be too obvious, but he votes Republicrat, because it's the only way to stop Hitler.