That’s part of the gag. 
What I’m getting at is that the dialog was very furtive and sloppy, and didn’t sound like a performance or anything meant to be conveyed to an audience as humor…as if they were doing a rehearsal or preliminary reading of a script.
No, that’s the actual track. Spinal Tap (a parody band created in part by Rob Reiner) recorded it for a charity CD.
This covers 90% of “Christmas” music written in the last 50 years. They’re really pop love songs that happen to be set at Christmas. They’re not really Christmas carols, despite being rammed down our throats after Halloween.
(Unfortunately, “Christmas (Baby Please Come Home)” falls into this category, despite being otherwise completely awesome.)
And to the poster who loathed “Jingle Bell Rock” with the heat of a thousand suns … that also goes for its evil twin, “Rockin’ Around the Christmas Tree”.
“It’s the Holiday Season”: A moderately obscure song (most famously sung by Andy Williams, I think). It’s mostly harmless except for one line that makes me want to throw the hardware through a window:
So whoop-de-doo
And dickory dock
And don’t forget
To hang up your sock.
What the hell is that? Just lazy lyrics, and embued with a sense of ennui and snark that is most unbecoming to the season.
What the hell is “the new old-fashioned way”?
Maybe it has something to do with The Madison. Wikipedia says that dance incorporated a step which originated in around '33 (Shuffle Off to Buffalo).
An oxymoron
It’s not like I’ve thought long and hard about it, but I always assumed it just meant something that’s come back into fashion. Like recent hipsters, with their new old-fashioned facial hair styles.
I have thought long and hard about it (ok, not really) and believe:
“old fashioned” = singing Christmas carols around the Christmas tree
“new old fashioned” = rockin’ around the Christmas tree
Although RAtCT doesn’t rock by anyone’s definition of the term.
Or a popular dance using a step that’s about 25 years old? 
It was a top-20 hit for Brenda Lee in 1960, two years after its original release.
Also top 20 hits in 1960: “El Paso” (Marty Robbins), “The Theme from A Summer Place” (Percy Faith) and “Mr Custer” (Larry Verne).
I was hearing Its Beginning to Look a Lot Like Christmas last night and, with this thread in mind, noted how dated the line about wanting “a pair of Hopalong boots” is. Not only are these items no longer at the top of (almost, I suppose?) anyone’s Christmas list, the number of people who even know who Hopalong Cassidy was is likely shrinking daily.
RAtCT was the top Christmas song at the end of 1960 and stayed in the top-20 for a week into '61. Charting higher and longer than Bing’s “White Christmas” for that period.
In a similar vein: “Up on the Housetop” (which is probably one of the oldest secular Christmas carols–1860’s) has a line about some poor kid getting a hammer and lots of tacks. Gee, thanks, Santa…
That works, too. A new way of celebrating old fashioned traditions.
Factoid: Bing Crosby’s “White Christmas” was not his top selling single. “Silent Night” was. But since it was a religious song, he gave all the royalties to charity.
“Silent Night” charted three times (once as “Adeste Fideles”) and peaked at #7 whereas “White Christmas” peaked at #1 in three different years.
Adeste Fideles is O Come All Ye Faithful.