Lol duh. The first part is a thing I hear a lot of gay men claim, that all men are a little bisexual and straight men don't exist, but the second part is how they reply when you suggest that that means gay men don't exist.
THERE'S NO SUCH THING AS A STRAIGHT MAN. ALL MEN ARE AT LEAST A LITTLE BISEXUAL. WHAT? OF COURSE GAY MEN EXIST. I'M 100% GAY. TO SUGGEST WE DON'T EXIST IS ABSURD AND VERY OFFENSIVE.