Season 3, Episode 6 - The Cornhusker Vortex
Aired November 2, 2009
When Leonard feels left out after Penny has her friends over to watch a football game, Leonard decides to learn about the sport. Leonard calls on an unlikely source of football knowledge, Sheldon, who knows all about football from his childhood in Texas. Meanwhile, Howard and Raj's friendship is threatened after Howard causes Raj to lose his prized kite in a kite-fighting match.