David Bowie and Bing Crosby's "Peace on Earth/Little Drummer Boy" — which was filmed on Sept. 11, 1977, for Crosby's Merrie Olde Christmas special — remains one of the most absurd (but charming) TV duets of all time.

The odd couple huddle around a piano in a lavish home decorated for the holidays, singing a collaboration comprised of an original song, "Peace on Earth," grafted onto the classic "Little Drummer Boy." Strings swell in the background of the hushed arrangement, which is highlighted by braided harmonies, counter melodies that pirouette gracefully around one another and a gentle, murmuring chorus of "rum-pum-pum-pum" throughout.

Prior to the duet, Bowie and Crosby act out a hilariously forced-looking skit. The former arrives at the home looking for a friend, who ostensibly lives there and lets Bowie use his piano, but instead finds Crosby milling around being all festive. The pair makes small talk about the holidays and traditions — "We sing the same songs — I even have a go at 'White Christmas,'" Bowie quips — before he comes upon something that sparks an idea.

"Oh, this one," Bowie says and smacks a piece of sheet music. "This is my son's favorite. Do you know this one?" Crosby responds warmly, "Oh, I do, indeed. It's a lovely thing." Cue "The Little Drummer Boy."

As this interaction underscored, putting the men together was a bit of a head-scratcher. Crosby was in the twilight of his crooning career; Bowie, meanwhile, was gearing up to release "Heroes," one of his most avant-garde releases yet, and was at the height of rock stardom.

Watch David Bowie and Bing Crosby Perform 'Little Drummer Boy'

In fact, Merrie Olde Christmas also featured a striking promo video of Bowie performing the album's title track. This take is rather psychedelic, no doubt because of how he approached it. According to his official website, Bowie "sings an emotional live vocal over a backing track, with some not so subtle phasing and echo effects on his voice that may well have been added after the event."

His movements are even more artistic: Bowie looks straight into the camera, as if trying to hypnotize audiences, and is later shown doing some mime-like gestures — as well as doing the old trick of putting his hands on his shoulders with his back to the camera, as if he was making out with someone.

In a 2014 interview published in Billboard, Crosby's daughter Mary recalled a flashy Bowie entering the set. "The doors opened and David walked in with his wife," she recalled. "They were both wearing full-length mink coats, they have matching full makeup and their hair was bright red. We were thinking, 'Oh my god.'" Nathaniel Crosby, Bing's son, added: "It almost didn't happen. I think the producers told him to take the lipstick off and take the earring out. It was just incredible to see the contrast."

That wasn't the only potential hiccup: As it turns out, Bowie wasn't thrilled with being asked to sing "Little Drummer Boy." In fact, he "came in and said, 'I hate this song. Is there something else I could sing?'" Ian Fraser, who co-wrote the "Peace on Earth" portion, told The Washington Post in 2006. "We didn't know quite what to do."

Instead of panicking, he and two other men working on the special — Buz Kohan and Larry Grossman — hunkered down at a piano in the studio basement and spent 75 minutes working up the tune. Ever professionals, Bowie and Crosby perfected the new song in less than an hour.

Watch David Bowie Perform 'Heroes' on Bing Crosby's Christmas Special

Speaking in American Masters: Bing Crosby Rediscovered, Kohan noted that "Bing loved the challenge" of the arrangement, "and he was able to transform himself without losing any of the Crosby-isms that relaxed the feeling and the atmosphere that he would always create whenever he was on camera."

Crosby never saw Merrie Olde Christmas air in prime time: He died of a heart attack on Oct. 14, after a round of golf. The special aired posthumously, premiering on CBS on Nov. 30, 1977.

In an interview published five days before in Cleveland's The Plain Dealer, Merrie Olde Christmas co-producer Gary Smith admitted, "I was a little concerned originally that Bing and Bowie wouldn't work out — but they worked well together. And I'm sure Bowie feels proud that he had the opportunity to work with Crosby."

That might be the case — but in a 1999 Q interview, Bowie called the appearance "ludicrous," and then added: "It's wonderful to watch. We were so totally out of touch with each other. I was wondering if he was still alive. He was just ... not there. He was not there at all.

"He had the words in front of him. ... And he looked like a little old orange sitting on a stool. 'Cos he'd been made up very heavily, and his skin was a bit pitted, and there was just nobody home at all, you know? It was the most bizarre experience. I didn't know anything about him. I just knew my mother liked him."

Watch a Funny or Die Parody With Will Ferrell and John C. Reilly

In an even more bizarre twist, "Peace on Earth/Little Drummer Boy" arrived as a single five years later, in November 1982. Curiously backed by "Fantastic Voyage" from Bowie's 1979 album Lodger, the track became a massive U.K. chart hit, landing at No. 3 in early 1983. In the U.S., "Peace on Earth/Little Drummer Boy" was Bowie's last release for RCA Records, and didn't chart; however, a video for the song taken from the TV special received plenty of MTV airplay around the holiday.

Against the odds, "Peace on Earth/Little Drummer Boy" has become a holiday staple — one that's ripe for both reverence and parody. Actors Will Ferrell and John C. Reilly even did a loving, frame-by-frame recreation of the clip in 2010 for Funny or Die, that hilariously ended in fisticuffs.

It's a fitting tribute to an iconic song that started off with humble and uncertain beginnings — and ended up showing the softer sides of two legends, as Mary Crosby recalled in 2014. "They sat at the piano and David was a little nervous," she recalled of the taping. "Dad realized David was this amazing musician, and David realized Dad was an amazing musician. You could see them both collectively relax, and then magic was made."

