Finding out that Leonard has never had a birthday party thrown for him, Penny convinces the guys to create a surprise party. Howard and Raj are in on the idea, while Sheldon envies Leonard for never having the experience (due to bad childhood memories). However, when Penny finally convinces him and they go to the store to buy presents, Sheldon finds out that the customers in the store needs his help much more than Leonard, making the plan fall out of schedule.