Whether hot dogs and hamburgers are "trashy" foods to eat, and whether they are considered "real food" or not. I mean, what the fuck is "real food"?
And it got pretty heated too.
And another one about whether the song "Yellow Submarine" by the Beatles was about drugs or not, and whether the band was on drugs when they wrote it. I mean, sure the band did drugs, no doubt about that. But he was arguing that they were on drugs when they were writing that song and most of their stuff, when the band has said multiple times that they are sober when they write their songs, because it's really difficult to write music when you're high.
Both involved the same person too... Me and him tend to get into really stupid arguments a lot for some reason.
And another situation was where I was trying to play a classmate's guitar during some down time in band class. It was a really shitty, cheap guitar that wouldn't tune properly. I tried playing some chords on it, and it of course sounded terrible. I said "man, this guitar sounds shitty." And someone said "that's because you are playing jazz chords, and that's a classical guitar." When I told him that was false, because it is, he started arguing with me.