User:WaltK/Sandbox 5
From Tardis Wiki, the free Doctor Who reference
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 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.