Season 1: Episode 8 - The Grasshopper Experiment

The Grasshopper Experiment: Koothrappali is overwhelmed after his parents arrange a blind date, but he discovers he actually can talk to the opposite sex after a few drinks; however, complications set in when his beautiful date is more interested in Sheldon. Penny has started her new job as a bartender so Koothrappali decides to have the date at her restaurant, but he blows it and Sheldon ends up getting the girl.