These kids kids are tying to dis me, help?

Well, im in 8th grade and these kids in 7th grade keep trying to make fun of me. Im taller than all of them, most of them are midgets and they are annoying. It is on my bus, 3 guys and a 1 bratty girl, they just try to start something im just like F_off ya kid. but they don't stop they are idiots and they spray stuff. There really pissing me off. Please help!