From 1965 to 1977, Bing Crosby made an annual TV Christmas Special. In September 1977, he recorded "Bing Crosby's Merrie Olde Christmas," an English-themed special that imagined Crosby as a guest at the estate of his relative "Sir Percival Crosby," where he welcomed various visitors (including Twiggy!) to talk about the season and sing Christmas songs. The special debuted November 30, 1977. It was the last that Crosby made; in fact, he had died suddenly in October of that year and the special was aired posthumously, introduced by his widow.
The most famous piece to come out of Bing's special that year (and perhaps any year) was his collaboration with David Bowie. This Washington Post article from 2006 tells the story nicely: Bowie was asked to be on the program (he agreed after the producers agreed to air his video for the song "Heroes" as part of the show), and they expected that he and Bing would sing a duet on the song "Little Drummer Boy." But Bowie complained that he did not like the song and didn't want to sing it, and so with very short notice the show's producers had to find a Plan B. Working quickly in the basement of the studio where the special was taped, they wrote a new song in just over an hour. After less than an hour of rehearsal, Bowie and Crosby taped the now-famous duet version of "Little Drummer Boy," with the brand newly-written "Peace on Earth" over the top.
Bowie would later say that "[i]t was the most bizarre experience," and that Crosby "looked like a little old orange sitting on a stool...there was just nobody home at all, you know?" For his part, Crosby called Bowie "a clean cut kid and a real fine asset to the show" in an interview a few days after the taping.
Since the show aired in 1977, the song has become a Christmastime staple, with regular rotation on Christmas radio and (back when they actually played videos) repeat broadcast on MTV and VH1. We're all the better off for it.
Here's the whole show on Youtube (Bowie's piece starts just after the 10 minute mark; his awkwardly-inserted "Heroes" video comes in at 31 minutes).
Bonus fact: For no apparent reason at all, in 2010 Will Ferrell and John C. Reilly made an almost shot-for-shot remake of the whole Bowie-Crosby bit (at least until the end). That same year, Jack Black and Jason Segel did an adapted, animated version.
Bonus fact 2: Bing Crosby is known now mostly for "White Christmas" and for being "one of those old-timey singers," but he put up some remarkable numbers over his career. As handily collected in the book "A Pocket Full of Dreams" by Gary Giddins:
* Bing has more studio recordings than any other performer in history (including 400 more than Frank Sinatra).
* "White Christmas" made an appearance on the record charts for 19 of 20 holiday seasons, from 1942 through 1961.
* Though the distinction is a bit dubious in the pre-Billboard, nascent record industry days, Crosby has had more songs make the charts, and more to hit number 1, than any other recording artist in history.
Bonus Fact 3: From this list, we see that "TV Christmas Specials" were a rather common thing in the 1960s and 70s; during his run from 1965 to 1977, in various years Crosby was in competition with Perry Como, Johnny Cash, Andy Williams, the Carpenters, The Captain and Tennille, John Denver and the Muppets, Mitzi Gaynor, Bob Hope, and Dean Martin.