*Yes, for the two of you who wonder about such things, this was on MPR. Cathy Wurzer does a music cue between segments towards the end of the morning show. Big shout out to Cathy while I'm mentioning her.
Now, I'm going to go on the assumption that we're all at least passingly familiar with the song at this point. If you're not you should google it now and come back when you've given it a listen.
OK, I'll go on.
Now, obviously the joke is that the kid singing the song (that'd be the '1st person narrator' for you pretentious academic types) doesn't realize that.... oh Crap... wait a second...
UNDER 11'S SHOULD STOP READING NOW
The kid doesn't realize that 'Santa' isn't real and that that is clearly Daddy in a Santa costume and his kissing Mommy is not particularly notable but for this comical misunderstanding.
I'm sorry you had to find that out here.
My point is that the Kid in question does not know this. So we have to view his responses through that filter
And this is all well and good until we get to the end of the chorus, where the lyrics take a disturbing turn-
'What a laugh it would have been
If Daddy had only seen
Mommy kissing Santa Claus last niiiiiiight'
OK, what the Hell are we supposed to make of that?? (outside of the fact that with a Midwestern American accent 'Been' and 'Seen' don't rhyme in any way whatsoever - but that's not relevant right now)
Theory One -
The kid hates Daddy. Possibly Daddy is abusive, or just didn't buy him a Playstation or something. You know, something that would piss kids off. The kid is wistfully longing for Daddy to be there to see Mommy's painful betrayal, perhaps hoping to gorge himself on the feast of Daddy's heartbroken tears.
Take THAT, Daddy. Mommy's a 'Ho. Bet you wish you'd bought me that Wii now, don't ya.
Theory Two -
The kid loves Daddy. But Daddy is hopelessly trapped in a loveless marriage to Mommy. Perhaps Mommy is abusive to Daddy. Or just doesn't put out. Or hasn't aged well. Whatever. Daddy longs for a divorce so that he can find a younger, prettier Mommy, but his strict Catholic upbringing forbids such a thing without due cause. Can this be Daddy's hope? Finding Mommy macking with an anthropomorphic personification of yuletide generosity? Hot Damn! Daddy struck Christmas Ho Gold!
Theory Three -
The kid is a sociopath and just wants to revel in destruction.
Regardless of which horse you pick in this particular race, we have to acknowledge that - laugh or no - Daddy is not there to witness this scene of Holiday Slut-Shaming. (as far as the kid knows). I therefore present to you the inevitable conversation being had the next day-
KID: Daddy, can I talk to you?
DADDY: Sure, Son or possibly daughter. What's on your mind?
KID: Daddy, there's something I need to tell you. I think you should sit down.
DADDY: Gosh this sounds serious.
KID: Dad, there's no easy way to tell you this, so I'm going to abandon the infantile variant on your title and talk to you man or possibly woman to man.
DADDY: Done and Done.
KID: Dad, have you ever noticed Mommy talking about... you know... any specific holiday figures...you know... in a way that might strike one as... possibly lascivious?
DADDY: Where the Hell did you learn the word 'lascivious'?
KID: Dad, Mom's giving it up Christmas style. I saw the whole thing.
DADDY: I'm sorry, what?
KID: He put his present in her stocking Dad. Right there. Right under the tree you paid for.
and it only gets uglier from there.