Can a person get bullied for something that they are not?

When I was a kid kids got bullied: because their parents were authority figures in the community, because they were socially awkward, because they were tattletales, because they weren't as attractive as others, there were probably other reasons. Looking back, the popular kids didn't bully others. The kids *who aspired to be more popular* were mean, trying to elevate their own status. One of my friends had children who were threatened because they were smart and participated in class a lot. The bullies told the child, "you're making  the rest of us look bad."

Back when I was in school, I think most gays were still closeted. There were rumors about one girl; I don't think she was bullied per se, but most kids avoided her if they could. I have no idea if she was or wasn't gay. None of my business.

without exception the bully is always the gay one.

they victimize others because they have issues dealing with their own sexuality.

or they literally want to roll around on the ground and dry hump you.

That's highly improbable.