In "The Bat Jar Conjecture" (Season 1, Episode 13), the guys kick Sheldon off their Physics Bowl team due to his ego, prompting him to form a rival team, while Leonard attempts to appease him with a Batman cookie jar. The episode is notable for Leslie Winkle joining the team and a meta-prediction by Raj, who suggests recruiting actress Mayim Bialik, referencing her real-life PhD in neuroscience two seasons before she joined the cast as Amy Farrah Fowler. More details on the episode can be found on fan forums like Reddit and the Big Bang Theory wiki.