I want to get my co-worker fired
What have they been doing to warrant getting fired?
He is very annoying because he doesn't stop whistling
You should be more open and honest with your co worker by politely asking him to stop whistling. You should not take it to the extreme of getting the person fired.
He whistles very loudly every time, it's common sense to ask him to stop.
Then I believe you should tell him to stop, instead of going immediately trying to fire him. Sometimes just a simple heads up can change the game, and you wouldn't have to go through such drastic measures.