"The Guitarist Amplification" is the seventh episode of the third season of the American sitcom The Big Bang Theory. This episode first aired on Monday, November 9, 2009.
In this episode, Leonard and Penny have fight over her former boyfriend and guitarist will be sleeping on her couch while he is visiting, causing Sheldon to revisit his traumatic past when his parents fight.
Sheldon invented his own board game: Research Lab ("The Physics is Theoretical, But the Fun is Real!") Sheldon is using Penny and Leonard as beta testers playing the game with him. They quit because Penny has to pick up her friend Justin from the airport. Justin plays the guitar and has a lot of stuff. He will be crashing on her couch for a couple of weeks while he finds some recording studio time. Leonard is shocked and wonders how close of a friend he is. He and Penny went out once or twice, but were never serious. Leonard, her boyfriend, doesn't like him in her apartment. Sheldon wants to get back to the game. As their fight excessively heats up, Sheldon gets emotionally upset and goes over to the kitchen and turns on the sno-cone maker to drown out the argument. Penny gives up trying to talk over the blender and leaves, while Leonard has won the first game of "Research Lab," and a celebratory sno-cone.
Leonard is still complaining about Penny in his car on the way to work. Sheldon doesn't appear to be getting used to people fighting. Leonard keeps complaining, causing Sheldon to jump out of the car and walk.
With only have seventeen minutes for guys to get to the movies, they run into Penny, who hopes Leonard is ready to apologize. Leonard doesn't and Penny again reads him the riot act in front of Howard and Raj. Sheldon leaves.
Killing time before the next showing, they go to the comic book store. Howard agrees that Penny was out of line, but she'll probably have a new boyfriend by this time tomorrow. Leonard will have to build a new girlfriend. Raj thinks Leonard is wrong. He tells about the time he took a cooking class with Howard, but Howard blew him off to do a liquid cleansing diet with his mother. They start arguing about his mother which freaks Sheldon out, now rants over his parents' argument before he storms out.
Sheldon goes to the Cheesecake Factory supposedly to have lunch to ask Penny to apologize to Leonard. She's not doing that. Sheldon mentions several complaints Leonard has about her: her driving, the bed full of stuffed animals that stare at him during their "amorous activities," her tardiness, or her singing. This revelation ticks Penny off even more. Her message to Leonard is that he can drop dead!
Sheldon quickly goes home and suggests to Leonard to apologize to Penny before she gets back. Before Leonard could answer to Sheldon, Penny angrily comes in to yell at Leonard over the list that Sheldon detailed to her. Sheldon suddenly disappears from the apartment in the middle of the fight, causing both Leonard and Penny to find him, who are still arguing. Sheldon goes to Raj’s apartment who is having a fight with his parents over coming to New Delhi for Cousin Sanjay's wedding. Sheldon again leaves. He then rings the doorbell at Howard's house, but after overhearing Howard and his mother fighting, Sheldon leaves before Howard can answer the door.
After driving around, they find Sheldon at the comic book store where he made a nest according to Stuart. Leonard describes how he pretends to be in an alternate universe where Leonard and Penny don't exist. Sheldon comments that he shouldn't flatter himself because he is just ignoring them.) Leonard and Penny try to convince him they're done fighting.
Leonard and Penny still haven’t resolved the Justin issue, though Penny tells Sheldon that in a relationship and people sometimes fight, but that they will always love him. Still sounding like Sheldon’s parents they buy him a toy robot and a comic book so that he will come home. Leonard, sounding like his father, complains that he'll just play with it twice and it will end up in his closet.
Finally while Leonard and Penny have restored their relationship, Justin is asleep on Leonard’s couch right next to Sheldon, prompting Sheldon to say "I should have asked for much more than a comic book and a robot."
- Title Reference: Penny's visiting friend's occupation as a professional guitar player.
- This is the first time, Sheldon makes a sno-cone without his Original Snoopy Snow-Cone Machine, which will appear in "The Irish Pub Formulation".