I'm so annoyed by my class mate. I'm going to have to tell him to be quiet.
Why would you say that to a classmate?
They won't stop talking, it's irritating.
It would be rude to tell your classmate to shut up. Find a more polite way of asking them to be quiet.
Shit I better say it in a nicer way.
Maybe you could tell him you have trouble concentrating when there is a lot of talking. Maybe he will get the jist and it won't sound too rude.