User:WaltK/Sandbox 5
In "The Dumpling Paradox" (Season 1, Episode 7), when Penny stays over at his and Leonard's apartment for the night, Sheldon is dismayed to find her still asleep on the couch the next morning, as it disrupts his Saturday morning ritual of getting up at 6:15am and watching Doctor Who on BBC America. Sheldon eventually gets to turn the show on to watch "the last 24 minutes" of the show, admitting that at that point it was more like "Doctor Why Bother".
In "The Justice League Recombination" (Season 4, Episode 11), the group go to a costume party at Stuart Bloom's comic book store for New Year's Eve. Stuart himself is dressed as the Fourth Doctor at the party.
In The Beta Test Initiation (Season 5, Episode 14), Sheldon and Leonard are watching an unidentified Doctor Who episode with their respective girlfriends, Amy and Penny. Amy remarks that "for somebody who has a machine that can travel anywhere in time and space, Doctor Who sure has a thing for modern-day London" (contrary to this statement, the music that can be heard coming from the television is actually from Silence in the Library, which is not set in "modern-day London"). Sheldon responds by warning her that "that's the kind of sass that can get a person uninvited to this year's Who Con". Penny, meanwhile, complains to Leonard that she was hoping to spend the night doing something more interesting than watching TV, to which Leonard asks, "even Doctor Who?" which Penny affirms. This prompts Sheldon to revoke her invite to Who Con.
In The Holographic Excitation (Season 6, Episode 5), the Halloween party at Stuart's comic book store includes a TARDIS in the back room that apparently doubles as a photo booth. During the party, Leonard and Penny emerge from it after having evidently had sexual intercourse. Earlier in the episode, Sheldon and Amy attempt to figure out a couples costume to wear to the party that they both like; included on a list that Sheldon makes up of potential couples to dress as is "The Doctor and a Dalek".