If Billy manages to hear anything over the sound of any running water, he has the sense to realize it's not any of his business and John probably needs the time to himself. Besides, he pops out for a minute to find them a bottle of something to drink before popping back in.

He probably shouldn't encourage the habit, seeing what John becomes later in life. But he's pretty sure John's probably already been into that -- and maybe worse than alcohol by now. One bottle isn't going to do any more damage.