I didn't think they could do anything but kick you off the bus. Someone on my bus passed their pass out of the window of the bus to their friend who then used it to get on and was busted when an inspector got on. Whether it's different because they're students or not I don't know, but you could always just give them a fake address if they ask for one. It's no wonder people use fake bus passes anyway when some bus companies are being investigated by the competition commission.