The Big Bang Theory Season 1 Episode 12
The Jerusalem Duality
Sheldon becomes insecure over his intelligence because of a smarter 15-year-old prodigy Dennis Kim. Losing faith in his own research, he annoys his colleagues by criticizing their work. He decides his work is useless and he aims for the Nobel Peace Prize by creating a "Nuevo Jerusalem" for the Jewish people to create peace in the Middle East.
The guys become sick of Sheldon's craziness and decide to try and take Dennis out of the picture by distracting him with girls. At his welcome party, their plan works when he leaves with a 15 year old girl for the mall. Excited, Sheldon returns to his old work. The rest of the boys are excited to have Sheldon back but are confused at how Dennis can get girls and they can't.