Okay, sure, this is meant to be somewhat whimsical, but think of the visual: a kind, wonderful, loving old woman is walking home on Christmas Eve, and then she gets run over by a reindeer.
And this is when the story gets horrible:
"Grandma got run over by a reindeer.
Walking home from our house Christmas Eve.
You can say there's no such thing as Santa,
But as for me and Grandpa, we believe."
So Grandma perished because of this? But reindeer fly, so how did they run her over? This song brings up a whole bunch of logistical questions.
This song, by the way, after studying this last phrase, fits perfectly into Christmas because of the modern Christian value of if you don't believe in Jesus, you are shunned. Grandma didn't believe in Santa Claus.
Check this out:
"When we found her Christmas morning,
At the scene of the attack,
She had hoof-prints on her forehead,
And incriminating Claus marks on her back."
So, it was a calculated incident. This song is about the most kind, benevolent fictional character of all time that spends his entire life making and delivering toys to children taking time out of his schedule to slay an old woman (who isn't even part of his target audience).
"Now were all so proud of Grandpa
He's been takin' this so well
See him in there watchin' football
Drinkin' root beer and playin' cards with cousin Belle."
So Grandpa's just fine with this, apparently.
The concept of Santa Claus moonlighting as an assassin for hire is not only terrifying because of his supernatural powers of light speed and work ethic, but because he can see us when we're sleeping, and when we're awake.