You should never have to say hello or goodbye. Even at work sometimes, and I know this is very unpopular, is that if I'm going to work every single day, I don't think you should have to hug people hello every single day when you come to work. I saw you Monday!
I'm on so late I'm definitely the last seconds of anyone's attention. So I just want to give them something dumb to laugh at, so they go, 'That's funny,' then fall asleep.