When the colleague that you're arguing with on a slack channel is an administrator. He has the power to delete anything you post that makes him look like a dick.

I will not submit to this reign of tyranny!

That's when you have to take the high road and just not argue. If he's an admin, he also has the power to make you look like an idiot.

Well he was only an admin on slack. Just junior level gopher of the office who wrongly got appointed administrative rights according to the office manager.

Next time he starts an argument, and is always him, he'll have nowhere to hide from me.

omg yes, this is my life. Only he has final say on all PR too.