Today I told my lazy & useless coworker "you may as well clock the fuck out and go home" and the only responsebI got was "you sure man"?

"Yes I'm absolutely sure, you're completely useless".

It infuriates me that I work all day (including picking up his slack, so basically I perform the work of 2 people) while he stands around with a phone in his face and earbuds in, yet gets paid almost the same as I do.

I've mentioned this to management (as have others) and they don't do anything about it, so I have taken it upon myself to play manager as well and send him home almost daily for the last month.

You have a job, fucking do it. You're already here.

Waste of air.