If you only know about the Pink Triangle from the Weezer song named that, then you need to learn some more queer history. See, the pink triangle is used across America as a symbol of gay pride — it's a mark that says, "Hey, look, I'm gay, ain't that great." It's branded on buildings, as part of organizations, and worn on people's clothes in a way to mark them as queer.
That whole "in clothes" thing is actually how it started, just in a very, very negative way. See, back in the Holocaust (yep, we're going there), people were arrested for a bunch of different things. The soon-to-be victims were marked with different triangles, according to their "crimes." You know the overlapping yellow triangles for Jewish prisoners, but there were a bunch of others, including one for communists, one for normal criminals, and one for homosexuals. Guess what color their triangle was? Pink, indeed.
Yep, a symbol of horror from the Holocaust later got reclaimed as a symbol of hope and pride, because honestly, what other choice did the queer community have? It's not like there were a bunch of great options for them in the first place.
