I like someone but not sure if they are gay. Do Brazil guys usually wear briefs?

I try to not hit on or try to come on to a straight guy. No one would guess I am gay, which is fine, but does get annoying when people assume I am heterosexual (which is why I am asking about this guy).At any rate, I have talked to him a few times and thought he was cool and wanted to be his friends (that's it). Today when I went to the gym and went to go wash my hands. He came out of the shower and said hi to me and started a conversation. I turned around and he was drying himself and he was just wearing briefs.We chatted as he was getting dressed and I asked him if he wanted to get a meal next week. To which he said, yes ( it was casual).This is early but I was wondering if straight guys usually wear briefs? He is Latin American (Brazil I think). Anyway might be a dumb question but thought i'd ask