"America is a democratic-republic, not a true democracy. In a true democracy, majority rules. If a majority wants you killed, you die. That's why a true democracy is actually insane." - some dude I work with
This is one of the goofiest things I have ever heard him say, and he says a lot of dumb shit.
It's a common thing rightwingers say—"America is a republic, not a democracy!"—because they know at some level that their ideas are not popular and that if elections in the USA were actually fair, they could never win. I think it's true, though, that amerikkka is a republic—a slave republic, just like Athens and Rome, where the only people with any kind of political power are the ones who got rich by crushing everyone else.
Tell them that, while the "archy" of words like oligarchy means "rule" or "command", kratos means "power" or "strength", and that demos is "the common people".
A true democracy, therefore, is not rule by the majority—that would be ochlarchy or, more commonly, ochlocracy, ochlos being the "masses"—but an empowerment of the common people.
And that they're right, America is not a true democracy.
The kind of majoritarianism he dislikes is bad, though, so I'd tell him he's right to be concerned for the protection of minority rights, but the empowerment of "the common people" necessarily protects all people, or else it would create a more powerful group, who could not therefore be common, so a true democracy is actually what he wants.
Ridiculous examples are the most fun to find some kernel of agreement and then spin to the conclusion of "you're right, anarcho-communism is the best way forward for America".