We were bitching about on of the managers at work last week and I was like, "Yeah, I can't believe he said that to you, I'd be like why don't you go fuck yourself, buddy?"
That was about him though, not to him. To him, I just say what's up man?
I'm trying to remember the last time I had occasion to just tell somebody to go fuck themselves, and can't really come up with it. That's kind of a shame, I used to be much more hardcore.