Having mates is so much easier when your a bloke, and no I'm not trying to push male superiority, just here me out.
When my mate started being a tool, I hit him. He hit me, and I hit back, and it stopped when we were both badly bruised and bloody. We both got suspended from school for 3 days (school policy), and you know what we did?
Day 1: Had a game of golf
Day 2: Went to see Pirates of the Carribean
Day 3: Had another game of golf
Fighting my mate saved our friendship, I don't condone taking this sort of action (call me a hypocrit if you like), but sometimes you just need to hit people upside the back of the head to keep them in check.