Pulling Pigtails

Why am I mean to the people I like the best? I am polite to strangers and acquaintances, but I take the most terrible liberties with my companions.
My sometimes cruel words are delivered playfully or with a smile, but the snarky comments I make to friends about themsleves, myself, and our relationships are harrassing and rude and I realise it.
I have thought about this bad trait and I think I know why I do it. Though it isn’t at all conscious at the time, I want more control or dominance in the friendship; I want a different friendship than what I have (either more or less intimate); or I need to show off to third parties my level of knowledge of my friend’s inner life or our relationship.
I don’t like it and I don’t want to do it, but I’m not sure how to stop myself. Why can’t I just be nice to the people I love?