S12, E4: When Sheldon won’t tell anyone why he’s never mentioned Tam (guest star ROBERT WU), his childhood best friend, Leonard takes matters into his own hands. Also, Bernadette and Penny take out Raj’s fiancée, Anu (guest star RATI GUPTA), for dinner to get all the details on her. JERRY O’CONNELL returns as Sheldon’s brother, George.