This is about a man who's can't take anymore. The jolly cheeriness surrounding the Giftmas season just doesn't apply to him. He's been laid off. He's been drinking his way to the abyss. On the drive home, seeing the houses lit up so festive, he snaps. He remembers the shotgun in the trunk of his car. His gift for his family is a shotgun blast sparing them a grim tomorrow. This is the song he hears in his head; that he sings to himself.
I'm sure it'll offend someone. And if you know that someone, well, send it to them. Merry Giftmas.
P.S. THIS IS NOT AN ENDORSEMENT OF VIOLENCE. It is intended as dark humor, a grim situation juxtaposed against an otherwise cheery setting.