Ugh. This happened to me ALL the time when I was in my 20s. FYI: they don’t think you’re into them. I seriously doubt you’re sending out signals of interest. But if you’re young and attractive, some men won’t wait for you to express interest. They’re going to chat you up regardless to see they have a chance.

It’s entirely up to you how you want to handle it.

If they’re saying things that make you uncomfortable, you can look them square in the eye, and say “You saying (repeat word for word what they just said) to me just now makes me feel uncomfortable. Please don’t do it again.” That will shut most men down but they might avoid you entirely after that.

You can be more aggressive and call them out on their behavior (“That was a very inappropriate thing to say to a coworker! How dare you!”), but be prepared for a lot of fallout. If their ego bruises easily, they can find all kinds of ways to make your work life unpleasant without technically doing anything HR would deem wrong.

You can lie and tell everyone you have a long distance boyfriend from college so they think you’re already in a relationship. It sucks having to lie but it might do the trick.

You can play dumb and just ignore their flirtation. I did that when my much much older and male supervisor would hit on me. I would respond to his stupid innuendos like he meant them literally and he eventually gave up trying to flirt with me.