The mid-season finale of "The Big Bang Theory" was a sweet and sentimental holiday-themed episode that revolved around Howard, Sheldon and Raj's mission to remove a pigeon out of a university lab and Sheldon's plot to ruin Amy's Christmas with the perfect gift.

Sheldon has made it clear that he hates Christmas, which is why he became upset when Amy decided to force him to attend her traditional Victorian Christmas Eve dinner. As a result, he tried to seek revenge against his girlfriend by buying her a heartwarming Christmas present after they agreed not to exchange gifts. His plan was to surprise her with the gift and make her feel guilty for not getting him anything.

In the meantime, Leonard and Wolowitz ran into trouble while they were spending Christmas Eve in the lab at the university. They called on Raj to help them remove a pigeon from the clean room. However, once they managed to successfully free the bird, a crow flies in because one of them accidentally left the door open. That's when they decide to take Penny's advice and erase all evidence that they were in the clean room and leave it in disarray.

Once the guys arrive at Amy's Christmas dinner, Sheldon presents his gift to Amy, which is a picture of him sitting on Santa Claus' lap inside of a musical picture frame. Of course, Amy absolutely adores the gift. However, to Sheldon's dismay, she feels neither guilty nor regretful, and instead gives him a Christmas gift. Sheldon opens the gift and finds that Amy baked him cookies using his Meemaw's special Christmas recipe.

"They're perfect. It taste like her hugs," he tells her, realizing that both he and his girlfriend are happy, notes Entertainment Weekly.

The next all-new episode is titled "The Space Probe Disintegration." According to Carter Matt, the synopsis reads as follows:

"When the guys finally agree to do something the girls like, it leads to a confrontation between Leonard (Johnny Galecki) and Sheldon (Jim Parsons)."

"The Big Bang Theory" Season 8, Episode 12, "The Space Probe Disintegration," will air on Thursday, Jan. 8 at 8 p.m. on CBS.