"The Proton Displacement" episode of The Big Bang Theory starts off with Leonard, Penny, and Sheldon shopping in a drugstore. Sheldon spots Professor Proton standing in the pharmacy line. Sheldon a introduces his girlfriend Amy to Professor Proton, and Professor Proton says, "Hold on, you have a girlfriend?" Amy points out that she's wearing the same orthopedic shoes as Professor Proton. Professor Proton says, "Oh, I get it now." Howard tells Raj that Bernadette's having a girl's night on Friday and asks if Raj wants to do something, but it turns out Raj is going to girl's night to make jewelry. Leonard tells Sheldon that he got an email from Professor Proton asking for help on a paper about nano vacuum tubes. Sheldon is upset that Professor Proton didn't come to him first. Sheldon whines to Amy about Professor Proton not coming to him for help, and Amy suggests that maybe Professor Proton finds Sheldon a bit much. Amy starts to suggest that Sheldon can be annoysing, but she stops short of finishing her sentence. Sheldon says he knows she was going to say annoying. Raj is at girl's night with Bernadette, Amy, and Penny. They are making necklaces with glue, when Howard shows up and offers to get his soldering gun to help. Sheldon shows up at Professor Proton's house in the middle of the night and tells him that his girlfriend suggested that Professor Proton might find him annoying. Professor Proton says apology accepted and tries to close the door on Sheldon. Sheldon offers to help Professor Proton with his paper now that they are friends again, but Professor Proton says he thinks he'll stick with Leonard. Sheldon pushes Professor Proton to say he's annoying, and Professor Proton obliges and shuts the door. Leonard and Professor Proton are working on their nano vacuum tube project, when Sheldon interrupts with Bill Nye the Science Guy. Bill Nye says his career would have never happened without Professor Proton, and Professor Proton says that's what he told his lawyers. Billy Nye tries to help with the project, but Professor Proton says, "Back off, bowtie." Raj is making necklaces with the girls again, when Howard shows up with more tools to help them. Raj seems annoyed that Howard is intruding on girl's night. Leonard is working with Professor Proton when Sheldon sends Leonard a picture of himself with Bill Nye the Science Guy. Professor Proton asks Leonard why he puts up with Sheldon, and Leonard says that Sheldon is the smartest guy he knows. He adds that Sheldon might be a little broken but they need each other. Leonard gets a text from Sheldon that Bill Nye ditched him at smoothie place. Raj gets upset and tells Howard that he's intruding on girl's night. Raj tells Howard that he likes hanging out with the girls because they don't make fun of him. Howard says he's sorry. Professor Proton goes by the Sheldon's apartment and tells him that he would like to get his opinion about his paper. When Professor Proton starts to hand Sheldon his paper, Sheldon reveals he already hacked into Professor Proton's email account and read it. After expressing concern over Professor Proton using his birthdate as a password, Shelton says he found the paper inspiring. Sheldon invites Professor Proton in for tea, but Professor Proton says he has to run. However, when Professor Proton realizes Penny is there he say she has time for a cup after all. Raj brings Howard a lightsaber belt buckle that he made for him. Raj says he has one to, and then suggests that they can have little swordfights whenever they want. Professor Proton is having tea with Leonard, Sheldon, and Penny. Sheldon is telling Professor Proton about his eighth favorite episode of his show. After Sheldon leaves, Professor Proton asks Penny if she has any single grandmothers. Penny says they are both married, and Professor Proton asks, "Happily?"