Getting harassed by high school girls

If I could drive to work I would, but I cannot afford parking and paying to sit my car somewhere disgusts me. So I take public transit, meaning when I get off work, I am often stormed by high schoolers. I don't want to sound arrogant or weird, but I am 21 and get told I'm good looking so I am aware what certain people think when they see me.

High school dudes tend to leave me alone even if these palm tree haired zoomers look like theyll rob me if I look at them. But the girls just straight up harass me. I am prompted to write this in part due to a very bad experience, where I foolishly sat in a booth seat on the street car, where I was then surrounded by hs girls in the empty seats. One girl kept looking at me and her loud friend just started making loud sexual sounds at me, and so I had to get up and leave embarrased around everyone. Other times I would get recorded by them in very obvious ways or theyll walk into me on purpose. If I stand, even if there are empty seats theyll stand around me.

Why do they do this/how to avoid this?