I generally don't do time outs - except in cases where my kids hurt each other.

Our 2 year old has taken to grabbing fist full of his big brother's hair and pulling hard/hurting him. It usually happens when I am not there to intervene. I like the whole be there to stop it thing - but mostly it happens when they are playing alone or I'm getting ready for work. Sometimes it is for NO reason and sometimes it is a dispute over a toy. The 2 year old laughs about it. If I take him to time out he laughs. If I put him in his crib, he climbs out. I've yelled at him (oops). Nada. He keeps doing it.

Any suggestions?