Annoying Mannerisms

My classmates have the most annoying mannerisms ever. One of them has a really bad laugh, states the obvious, copies people right after they say something, and agrees with everybody. Another one bites his fingernails, but that isn’t the bad part. He spits them at me all of the time.
Anything funny will make the one of them open his mouth really wide and snort. He likes to say stuff that people already know. He says something that you just said because he doesn’t pay attention to anyone when they’re talking. He avoids conflict by agreeing with everyone and saying “I know”, or “you’re right”.
One of my other classmates bites his nails and spits them at you. I don’t mind him biting his nails, but when he spits them at you it’s disgusting. The only other thing I hate that he does is he says things other people say. He doesn’t say it right after like my other friend, but it’s annoying and I hate it. If someone says something that he thinks is funny, then he says it, way too much, but just for a little while until he forgets.
Other kids in my class that I don’t know well have some mannerisms too, but they’re not as annoying. One of them uses his hand to gesture when he talks. If he is holding anything he throws it by accident. Another one used to sing and everybody hated it. Some of them say stupid things and are really mean without thinking before they talk. But most of them crack their fingers, say weird things, have weird laughs, or just stuff like that.
I’m sure I have some annoying mannerisms too, but I don’t know them, and I bet everyone is annoyed by them. I hate annoying mannerisms and wish no one had them.