Sheldon only lists that Tam 'knows what he did'. Howard downloads the enemies list from the Internet and finds Tam Nguyen. Then he changes his mind on asking them to do something about his name on the list for urinating in Sheldon's shampoo bottle before signing off. George wonders if he still has his enemies list (and bathroom schedule) and suggests looking it up. Leonard mentions that he was not even at the wedding, and George is embarrassed at realizing that he had a long conversation with a guest he thought was Tam. Tire, he remembers Sheldon's вЂњlittle Vietnam buddyвЂќ. Later Skyping with George in his office at Dr. They all wonder what Tam could have done so Howard suggests that they call Sheldon's brother George. Since Leonard knows Sheldon's bathroom schedule, he thought he knew who his friends are. She calls him, but he won't do it because it is illegal.ДЄt lunch, Leonard can't believe that Sheldon has another friend that Leonard has never heard about. Penny can't find anything on the internet so Bernie wants her Dad to check with his police buddies. In Bernadette's office, she is playing a video game when Penny enters and is worried about Raj and his new fiancГ©e. He seems to have betrayed Sheldon and Amy doesn't want to pry into why.

Bernadette wants to know if she has fingers.

Raj asks for advice on an engagement ring. In Apartment 4A having dinner, the gang wonders how Raj could be engaged to a woman that he just met. Sheldon hears from his boyhood friend Tam. Amy wonders why Sheldon never mentioned his childhood best friend so Sheldon yells at her, вЂњTam! Tam! Tam! Tam! Tam!вЂќ and runs into the bedroom. Amy then receives an email from ' Tam' telling Sheldon that he was visiting Caltech with his son and wanted to get together with his old friend Sheldon. Extended PlotДЄmy enters her living room to find Sheldon improving their wedding photographs by adding guests who did not attend like the Wright Brothers. Also, Bernadette and Penny take out Raj's fiancГ©e, Anu, for dinner to get the 411 on her. The resulting dinner that Penny, Bernadette and Anu have together may have some unintended consequences.When Sheldon won't tell anyone why he's never mentioned Tam, his childhood best friend, Leonard takes matters into his own hands.

Much like Leonard, Howard and Raj, Penny and Bernadette decide to take the direct approach in going to the hotel where she works as a concierge to introduce themselves. Meanwhile, Penny and Bernadette decide to do some sleuthing on their own about Anu, who Raj has decided to marry. They eventually do learn the reason from Sheldon, all his friends who try to bridge the gap from Sheldon back to Tam. After going through several channels without finding out the reason, Leonard, Howard and Raj do locate Tam on campus to find out directly from him, Tam who doesn't divulge why for a very good reason. While whatever the issue, Leonard, Howard and Raj believe that the reason will be nothing material to any normal person and thus without even knowing what it is, already side with Tam. As such, Sheldon has no intention of meeting with Tam. The reason?: Sheldon and Tam have not spoken in twenty years since Tam is now on Sheldon's enemies list, because, according to the list, Tam 'knows what he did'. Sheldon's closest group of friends wonder why Sheldon has never mentioned Tam before. Sheldon receives a message from his best friend in high school, Tam Nguyen, that he is coming to California to show his son around Cal Tech.

Big bang theory s12 ep4