There's this kid that I'm going to call an asshole.
What's is your reasoning for taking pleasure in insulting others?
No reason really. I just don't like him so I want to insult him.
Not liking him is fine, but that doesn't mean you should insult him. If that's how you treat people  then I'm sure there's quite a few that don't like you, so how would you feel if they all started calling you names? It would be pretty rude wouldn't it?
I'm a kid, so it doesn't matter as much.
Kid or not, it's rude to call others names and it certainly wouldn't feel good if you were in this kid's shoes. Rather than being petty and insulting him, you should just keep your distance since you don't like him. Share the company of people you like and focus on them.