In the “Futurama” episode “Xmas Story” (December 19, 1999), the Planet Express crew take a holiday jaunt to the Catskills for skiing and old-world comedy. The headliner at the Catskills Lodge (no pun intended) is the living, preserved severed head of Conan O’Brien (voiced by himself). In the world of “Futurama,” severed heads could be kept alive indefinitely in jars of mysterious, life-giving liquid, allowing 21st-century celebrities to organically appear in the show’s 31st-century setting. It’s been revealed that animating Conan’s massive noggin proved technically difficult. 

Conan’s severed head attempts a few jokes, but he is heckled by Bender (John DiMaggio) the alcoholic robot. Conan attempts to silence Bender by claiming to have a soul, a fact that doesn’t impress the robot. When Conan also points out that he has freckles, Bender is reduced to tears, knowing he, as a machine, will never have freckles of his own. 

O’Brien was no mere “get” for “Futurama,” however. O’Brien, as many of the comedian’s fans know, spent several years writing and producing “The Simpsons,” which was created by “Futurama” co-creator Matt Groening. O’Brien famously penned “Marge vs. the Monorail” and several other classic episodes before quitting to start his own talk show, and he remained close with his old “Simpsons” colleagues. 

As it so happens, the other co-creator of “Futurama,” David X. Cohen, also worked on “The Simpsons” as a writer, but was brought on as one of O’Brien’s replacements. Cohen and O’Brien never professionally crossed paths, and wouldn’t meet face-to-face until years later. By wild coincidence, however, Cohen was assigned to the very same office where O’Brien worked while at “The Simpsons,” writing episodes on the very same desk. 

Indeed, on the DVD commentary track for “Xmas Story,” Cohen recalls finding a wonderfully strange welcome note that O’Brien left behind.