Gay is pretty much homosexual. Yeah.
It's used by some people, either as an insult or a joke.
Mostly used by 7-15 year old guys.
Jake: Dude, bro, Matt is so fucking gay dude.
Johan: Yeah, I know right, so FUCKIIING GAAAAAY!
Matt: I'm sitting right here guys. And I'm not gay...
Jake: It's just a joke, hahahaha.....
Matt: Fuck you guys *walks away*