It can be a guy if your character is a straight/bi girl or a gay guy, yeah. In that scene he takes his dick out and masturbates and comes on another girl watching and possibly you.
My character is always bi and I've never seen this. Even when I have a Female BF it's always been a girl showing us her hoohas.
Edit: I just reread your comment. And you said if you're a girl or gay guy. I misread what you said. My bad.
With that context in mind I kinda wish it was more 50/50 like. If you're character is bi and you have a Female bestie. Then you'd have a 50/50 chance of spawning the Guy. Just like if your a bi Female with a male bestie you should have a 50/50 of spawning the Girl.
But either way that's pretty dope, and I didn't know about it because I'm always playing a bi guy character.