Doctor Who

Doctor Who is a long-running British sci-fi show. Matt Groening claims to be a fan of Doctor Who. Whenever the Doctor appears he is in his fourth incarnation as portrayed during the 70's by Tom Baker.

References to Doctor Who in The Simpsons
In Treehouse of Horror X, Comic Book Guy, aka The Collector, had the Doctor concealed in plastic, along with many other geek-show characters. He introduces the Doctor as Doctor Who (the character's common nickname) to Bart Simpson, aka Stretch Dude and Lisa Simpson, aka Clobber Girl. The Doctor also makes an appearance as one of the representatives of TV in Sideshow Bob's Last Gleaming and in Bart the Fink. Comic Book Guy is seen walking out of a taco shop with a hundred tacos, stating that they'll give him sufficient energy during the Doctor Who marathon. Tom Baker appears in his Doctor costume in the episode Mayored to the Mob.

In the episode Springfield Up, Homer says to Declan Desmond "Check with me in 8 years Doctor Who, I'll be kicking your ass with a golden boot!"

References to The Simpsons in Doctor Who
The Simpsons have also been referenced on the revived Doctor Who. In the episode Planet of the Ood, one of the Ood's programming functions is 'classic comedy', the Ood Operations worker says "Ood, you've dropped something", and the Ood replies with "D'oh!"

Also, in David Tennant's swansong episode The End of Time: Part 2, there is a possible in-joke: After being rescued, the Doctor is strapped to a wheelchair. As he's pleading with his rescuers to unstrap him, they wheel him down a flight of stairs. Halfway down, he shouts "Worst! Rescue! EVER!" very much in the manner of Comic Book Guy and his catchphrase.