When you want to narc on the coworker you hate to the boss but that coworker doesn't leave earshot

Growing up in a bad neighborhood I would say the saying snitches get stitches is actually true so it's best not to directly narc. If your coworker is going something wrong create and opportunity for the boss to discover it.

Grow a pair and do it in front of them. I don't sneak around.

I don't narc. I tell the boss "hey this guy wants this. Give it to him" 😂

Or if they're an idiot and cause a problem I write an incident report, file it and then keep it to myself so by the time I'm saying anything to a boss I have dated co-signed evidence that they're a problem. I also tell them to their face they're a problem because otherwise that'd be unfair.