This page explains in detail the interactions between the Donkey Kong series and The Big Bang Theory series.
The Big Bang Theory episode The Bozeman Reaction[]
January 18, 2010
Donkey Kong
The Big Bang Theory
The Big Bang Theory - Sheldon's Journal
In the thirteenth episode of season 3 (Episode #53), the main characters' apartment got burglerized and many of their videogames are stolen. In a scene, Sheldon is seen writing in his journal "out there evil lurks... Probably playing Donkey Kong on my classic Nintendo".
Oddly in a previous scene Sheldon listed all the stolen consoles and games, and while he did include the "classic Nintendo", Donkey Kong was not in the list. This either means that he didn't own Donkey Kong, and just said a generic game in the journal, or, more likely, that he forgot about the game while listing them, probably because of the shock.
The Big Bang Theory episode The Shiny Trinket Maneuver[]
January 12, 2012
Donkey Kong
The Big Bang Theory
The Big Bang Theory Donkey Kong had Donkey Kond Jr.
In a scene in the twelfth episode of season 5 (Episode #99), Howard, Raj and Leonard are playing Donkey Kong Jenga. They talk about Bernadette not wanting to have children, and then Howard comments how "even Donkey Kong had Donkey Kong Jr. So he could teach someone how to kidnap princesses and throw barrels at Italian plumbers."
Note that actually Donkey Kong didn't kidnap a princess, since he actually only kidnapped Mario's girlfriend Pauline. Also in the original game Mario was a carpenter, not a plumber, but his occupation was changed to plumbing in the Mario series.
License[]
The Big Bang Theory company Warner Bros. had no rights over Nintendo's property, but they only included minor references to Mario.