Rude friends

r/

In my poetry class ( kinda irrelevant but just felt like saying it ) I sit next to 3 people who are all a grade above me, friend 1 (16M) I’m not the best of friends with him and he is kinda weird but I don’t mind him, friend 2 (16M) I have been friends with the longest and is funny but also can be rude, friend 3 (16M) is also rude sometimes and I don’t like him very much but he can be funny, now there is another kid in the class, well call him person A (15-16M), he just minds his own business but I’m pretty sure he is a bit on the spectrum, I can tell because he kinda reminds me of my cousin who is a little bit autistic ( not a joke sorry if it came off that way), he sits funny sometimes by like crossing his legs and he bites on his pencils and stuff, I don’t really care but the problem is, friend 2 and 3 get a kick out of it and like messing with him, they like to whisper his name and stuff to try to get his attention and then quickly look away, I don’t like it when they do that, it doesn’t sit right with me at all, for example when person A sits differently they will start giggling almost and in wisper they say look at person A hehe, I wana tell them to stop how should I go about it? oh and friend 1 doesn’t say anything about it either but he also doesn’t make fun of person A,
TL;DR
My 2 friends I sit next to mess with some kid in the class, how do I go about telling them to stop.