[dusted]

I worked with a guy like that once, I was new and didn't feel secure, but after a while I decided that since he was an ass to me, I'd be an ass to him.

So one day he asked me to do something and I just said "no", and he asked me why, so I told him "because you're an asshole, and I don't like you, go do it yourself".

Everyone in the office heard this, nobody reacted. I found out it was okay. We worked together for 3 years after that, and while the tone didn't get much better, some mutual... something was found and we got along "just fine" (insults seems to hurt less and less over time, especially when you get to pay them back).