Leonard, Howard, Raj, and Sheldon are all incredibly smart men who have dedicated their lives to science. Their adult lives are full of positivity and friendship but it hasn't always been that way. Everyone (except for Penny) was bullied in their youth. And sadly, the bullying continued. Penny's ex-boyfriend bullied Sheldon and Leonard on two occasions: when they tried getting her TV back from him and when Leonard tried getting him to pay Penny the money he borrowed from her. In "The Speckerman Recurrence," Leonard also confronted his bully from high school.