How do I just make them SHUTUP!?

okay, idk what it is........but I can get SUPER aggravated at school somedays. So I have this 1st period cl for extra math help, and I'm kinda cool with this girl, but sometimes I be thinkin she tries to insinuate something..........and then joke around with this girl thats known for startin stuff. I have thic cl tomorrw, and if the girl says stuff bout me behind my back, I will tell her off. And everytime I tell some1 off I laugh about it afterwards cuz it be funny. So i like............need a way to make em shutup and not say nothin else to me...seriously!