Sheldon Cooper has something sinister up his sleeve this Christmas, and that is to buy his girlfriend Amy the worst gift imaginable.
In "The Clean Room Infiltration," Sheldon is seeking revenge on his girlfriend for ruining his Christmas plans.
"Let's find the kind of gift that makes her feel small and worthless," he tells Bernadette while the two are out shopping.
Sheldon is being a total 'Scrooge' since Amy decided to host a traditional Victorian dinner on Christmas eve instead of just doing what he wants.
Meanwhile, Leonard and Howard spend Christmas eve in the lab, only to get into an argument with each other and create a potential disaster. They seek the help of Raj, and the three geniuses later find themselves scrambling with a pigeon.
The Big Bang Theory Season 8, Episode 9 will air on Thursday, December 11 at 8 p.m. on CBS.