See, I AM the "cool" parent, but I'm also very open with him and have explained that yes, I am a friend, but I am also a parent, and it's my job to prepare him to survive in the world, and that means teaching him a lot and guiding him, which unfortunately means that I have to lay-down-the-law, and dish out punishments for 'bad' behaviour. I've sort of taken down that seemingly-insurrmountable wall of parent/child and made him aware of that power dynamic, made him a partner in shaping his rearing-years. Plus, I've often told him that parents can learn just as much from their children and we can both help eachother to become better people as we get older.
Unconventional, I know, but I don't treat him like a child in a lot of ways, yet, allow him total freedom to be childish, so he's in a way, a lot like me, very mature, yet still alive and vibrant with that glow of youth and the twinkle of mischief in our eyes.