The Big Bang Theory Episode 6.11 The Santa Simulation

Leonard tries to get Sheldon to warm up to the idea of Christmas by playing a Christmas-themed Dungeons & Dragons game. As the game progresses, Sheldon has an opportunity to save Christmas by saving the (fictional) life of Santa Claus, but he chooses not to because he holds a grudge against the bearded Christmas icon. In doing so, he reveals that he's hated Santa Claus ever since he was 8 years old, when he asked Santa Claus to bring his father back to him and Santa failed. In the end, the revelation (and fictional death of Santa) gives Sheldon some closure. Meanwhile, Koothrappali's character gets killed off in the D&D game early on, so he goes out with the girls on a girls' night and bonds with them. He reveals that he had a crush on both Penny and Bernadette, but not on Amy, so she spends all night flirting with him only to let him down at the end.