My coworker sarcastically called me "boss"

[alarimer]

Actually he wished me a "Happy Boss's day". I am not his boss; in fact we have the same title and position, though he has been there over 25 years and I have been there 10. What should I make of this? Honestly it pissed me off a little. I won't defer to him, so I get this sarcastic bullshit? 10 years is plenty long enough to know what I am doing. And I am sick of being walked on all the time (this guy treats other people generally like crap- so much so that when we have interns we will not let them work alone with him until we know they can stand up to him), so I am becoming more assertive. Well, I cannot stand this guy and wish he would retire already. He can barely do the job but thinks he knows everything and the world revolves around him.

I long for the day I can tell him to fuck off. I guess it will be when one of us leaves, preferably me.