Obviously numerous versions of "I Saw Mommy Kissing Santa Claus" have been recorded since Jimmy Boyd first did in 1952, but the best clearly was the one performed by the Jackson 5 on their 1970 Christmas Album.
It's not merely the pop mastery of the group or the production, but the way young Michael says just before the solo:
"I did, I really did see Mommy kissing Santa Claus, and I'm gonna tell my dad."
Why does that put it above all others? Let's examine.
All versions of the song have these lines to make it seem playful:
Oh, what a laugh it would have been
If Daddy had only seen
Mommy kissing Santa Claus last night
Conceivably we, the at-least-moderately sophisticated adult listener, know that the Santa whom Mommy is kissing is merely Daddy in a costume, and dismiss it as lightly romantic behavior between the parents after all the Christmas Eve tasks, after the children have been put to bed. And upon seeing his mother being so affectionate toward another man who appears not to be his father (we presume for the first time), the child dismisses it as laughable because, after all, it is Santa. How could his father be anything but amused? And we know that Daddy would be amused because it is, in fact, he who is receiving Mommy's affection.
We know that, but clearly the child does not.
The lyrics force it to come around to a non-threatening conclusion because, well, it's a Christmas song ostensibly about Santa and therefore must remain light in tone, but even cursory reflection on what is really happening shows the song always had a troubling subtext from the child's point of view.
That assertion (in what is presumably meant to be a quaint throwaway line) to tattle on his mother to his father gets at the heart of how traumatic seeing the apparent infidelity could be to a child young enough to still believe in Santa. It at least gives brief explicit mention of that subtext while still allowing the track to be something we can hear over and over every holiday season without feeling uneasy.
That's what Christmas ultimately is, even for those who have had very pleasant Christmas days: Something that is struck through with troubling elements that we pretend is an unmitigated good for the sake of the kids. Other versions simply ignore that first part, and that's why they are inferior.
We won't get into the obvious insinuation that Mommy and "Santa" are pretty kinky. (Either Daddy donned the suit to fool any children who might come down from bed, in which case they are unconcerned with their protracted fooling around being witnessed, or Daddy donned the suit because Mommy finds it a turn-on, and perhaps getting caught is part of the allure and hence the reason they are doing it out there by the tree rather than behind the closed doors of their bedroom.) Again, it's supposed to be something to be played again and again, and it's best not to be thinking about that., especially when a child is singing.
Happy (Don't Think About It) Holidays!