Work harassment, next steps?

I keep getting hit on very aggressively when I try to go out after work with everyone. I would say I need to be more masculine about it so they understand I do not like men like that. Usually it’s just the one, same guy. He is hard to avoid because if I move away, he eventually follows. Doesn’t happen at work.
I wanna keep going to socialize but don’t wanna cause drama by yelling at this dude.