I'm pretty sure you dare not mock them on their flows or goofy character or they'd get pissed. Reflect on that, friendships, even for men/boys aren't about putting someone down over something they can't control, you're their scapegoat bro, I hope I'm not misreading but it could be that you make them feel better about themselves. Observe them and try to see if they can't take their own medicine, call them out on what they do and say it's something you don't want them to make fun of, if they ignore it and keep doing it, they aren't your friends.