Through the seasons heвЂ™s made some happy holiday memories, though, like when Penny gave him Leonard NimoyвЂ™s used napkin from the Cheesecake Factory in season twoвЂ™s вЂњThe Bath Item Gift Hypothesis,вЂќ and when he and then-girlfriend Amy gave each other sweet gifts - homemade cookies from his grandmaвЂ™s recipe for him, a personalized photo frame with a pic of Sheldon with Santa for her - in season eightвЂ™s вЂњThe Clean Room Infiltration.вЂќ

Sheldon Cooper was initially a Grinch, hating on all things Christmas because his beloved Pop Pop died when he was 5, and SheldonвЂ™s Christmas wish - to bring Pop Pop back - was denied. HereвЂ™s our rundown of all the Theory-isms that continue to keep the CBS sitcom churning after all these years.ДЄs the amount of affection she was getting from now-ex-boyfriend Sheldon increased, AmyвЂ™s crush on Penny cooled, but during the early seasons of the ladiesвЂ™ friendship, Amy Farrah Fowler could not be less than subtle about her physical interest in Penny: She presented Penny with a painted portrait of the two of them, which Amy said had originally been a nude portrait she drunkenly kissed Penny in season fourвЂ™s вЂњThe Agreement Dissection,вЂќ and sang lyrics from Katy PerryвЂ™s вЂњI Kissed a GirlвЂќ and after Penny tried to explain SchrГ¶dingerвЂ™s Cat with a real-life example, Amy told her, вЂњHomespun stories, knowledge of physics, and a bosom that defies it. They love comic books, costumes, video games, and sci-fi in all forms of media, but what are the other recurring themes, jokes, and life experiences that make up Sheldon, Leonard, Howard, Raj, Penny, Amy, Bernadette, Stuart, and their Big Bang TheoryВ characters weвЂ™ve been following for nine seasons? Just as each of those characters can be largely defined by his or her eccentricities (we could write a book on Sheldon alone), some of those quirks also point to how much each of them has evolved throughout the seasons (even if some of them still have a significant way to go).

Schrodinger jokes