When you think you're the shit, and arrogantly turn people down and offend them.
The popular guy shitfucked the girl when he crumpled her love letter she gave him.
A "friend" who treats everyone the same, without paying close attention to any of them, and incapable of intimate reciprocal engagement; someone who is respectful and benign, but cannot form real close bonds with others.
Have you noticed that he's a socialist friend? He's nice and talks to everyone, but no one actually invites him to hang out outside of work.