If it's just a couple of teenagers and you actually get the chance to confront them, all you'd likely have to do is act like a crazed drill sergeant and they'd probably be terrified. Most teens are pretty cowardly when it comes to actual confrontation. An example:

My brother was riding to work one afternoon (he works at night) and a car passed by him and someone screamed at him. Nothing in particular, just a kid being stupid. Well it just so happened that he caught up with the kids at an intersection where they were trying to turn left in busy traffic. He calmly pulled to the passenger side window and leaned on his handlebars and waited. The kid who yelled was fiddling with his phone so he wasn't paying attention. When he finally looked up, my brother said his facial expression was priceless. My brother asked him, "Is there a problem?"

Kid: "What?"
Bro: "You yelled at me back there, I just assumed something was wrong."
Kid: "Oh...uh...no I was just saying Hi"
Bro: "No you weren't, you yelled at me."
Kid: "No man, I see you riding all the time so I was just saying Hi."
Bro: "So you say Hi to people by yelling? That's pretty strange."

By this point my brother tells me the kid looked like he was about to throw up, so my brother changed his tone a little and just asked him not to do it again. By the end of it, he introduced himself and told the kids to have a nice day. I think he handled it quite well. Much better than I would have!