1. People bought the game they can do as they see fit.
2. Most do it to try and get under your skin and throw you off your game. Apparently it's working.
3. If I get an awesome play, winning or losing I will dance and bag until said orbs vanish
4. You lag, I bag
5. If you bag, I bag
6. If I'm annoyed at you, I will bag so rapidly it should be considered a war crime
7. When is it appropriate to tbag? In the words of Severus Snape "always"