Blocking is possible but, since you call your roommate a noob (Someone unexperienced, a term usually used by awesome gamers like me) in tech matters, I won't recommend it. A smart method might be to surreptitiously stop the torrent on his device or, if you use a pc, to set connection mode to bridge and, revert back to pppoe when you no longer need the internet. A noob might call the local isp, scream at them and embarrass him self overall. Also, try reading two stories of how Kerala Police busted torrent downloaders. That works on a lot of people.