It's like an AU where instead of being a grim, distant father and a hyper competent hunter John is a clueless drunk. I'm guessing the only thing keeping this John alive is luck. Sorry if that was a little confusing before. I know that in the show John really wasn't like this.
"Now Sammy," John lectured, "one day I'm gonna need your help with this hunting gig. You're gonna need to know what to do. So I'm gonna tell you." He paused to pick up a pistol and carefully hand it to his young son, who started at it with a wide-eyed and innocent gaze. "Take this. You need to learn how to shoot it. We'll go into specifics later. But for now, just kinda point it at the target and shoot. You'll get the hang of it soon enough."
Sam lifted the gun and began to chew on the end of the barrel.
"Daddy! What are you doing!" a five year old Dean screeched from in front of the tv. "You said no playing with guns in the house!" He looked in horror at the crudely drawn target on the thin wall (between their room and their neighbor's kitchen).
The one year old Sam looked up at his older brother and smiled, accidentally pulling the trigger. The bullet shot through the ceiling, only just missing the tip of poor Sammy's nose.
"Shit!" Dean cried as the loud 'bang!' sounded through the apartment.
"Shit!" little Sam happily repeated after throwing the gun across the room.
"Eh, maybe it's time we moved to another town," John said awkwardly as the neighbors began to scream at them again. Even in his drunken state he knew the cops would probably be there sooner or later. He'd have to make sure they grabbed the stash of booze before they left; it would cost more money than they had to replace it and the boys might need to eat again soon.
Originally the gun was going to be unloaded, but I wanted it to go 'bang!' when Sammy accidentally pulled the trigger. I guess that would have made this John an even worse father...(it's a good thing he didn't actually do this sort of thing).