I just sent my 13yo ds to his room for attitude - again. This is my fourth son to go through this stage, and I am too old (and tired) to deal with this cr*p. He gets into grumpy disrespectful mode and is too stubborn to stop, even when he knows the hammer is coming down. This part of parenting is just NO fun. It doesn't help that his little sister, who is just 9 months younger, takes her cues from him and picks up the attitude.
Oh well, at least it's quiet with both of them sitting in their rooms.