In the PBS "American Masters" doc on Bing Crosby - coming in December -
there is discussion of the Crosby/David Bowie duet of Little Drummer Boy by
both the director and head writer for the Crosby Christmas Special where it
occurred. Bowie showed up (because his parents loved Crosby) and was told
they would sing LDB as a duet. Bowie refused as he hated that song and felt
it was too religious. The writers quickly re-wrote the number so that it is
Bing singing LDB and Bowie is singing a different song at the same time.
More on the Crosby documentary later.