No I do not think this is a harmless act because you should try and do mean and spiteful things. It can come back to you. If the person who is hacking know if someone was to hack them they would be mad. Treat others the way you want to be treated. Hacking is trifling & it shouldn't be done.

   If I got on a computer and someone's account was still longed in I would just log out of it. I really could care less about a persons facebook, or twitter. It's none of my business what they do or their accounts. In plus I would do what I would have want done to me if my accounts were still logged on. I wouldn't want people going through my stuff or writing things as my status.