CBS

Season 2: Episode 14 - The Financial Permeability

The Financial Permeability: When Penny runs into financial trouble, Sheldon gladly offers to lend her money. Penny is uncomfortable with taking money from him and begins to act out her frustration which confuses Sheldon entirely. Leonard soon finds out that her financial troubles began when she lent money to her ex-boyfriend, Kurt, who has never paid her back. Without Penny's knowledge, Leonard then decides to get the guys together to confront Kurt and get her money back. It doesn't go exactly as Leonard plans but soon enough Penny's ex shows up at her door and returns the money. Penny is so taken by Kurt's gesture that she believes he has changed his ways and agrees to go out on a date with him to Leonard’s dismay.