Die Streichelmaschine

Raj, Howard and Sheldon are singing karaoke and playing instruments. Then Penny comes in and makes fun of them. Leonard comes in and is busy on the phone. Sheldon, trying to read Leonard's gestures, announces that he is going to have a colonoscopy. But Leonard explains to all that it is actually just his mother coming for a visit.

When Penny goes to the washing room, she meets Leonard's mother on the corridor as she stands in front of the broken elevator. She starts talking to Penny and lets her accompany her upstairs. Penny asks her about Leonard's childhood, but Beverly Hofstädter remains cold and throughly analyzes Penny's few statements. She suspects that Penny has a problem with her childhood. She manages to get Penny to trust her, and Penny starts crying. She retires to the door wailing.

On the other hand, Sheldon is very pleased with Leonard's mother. They intently discuss the sexual relationship between Leonard's parents, which only occurs for the process of reproduction. She soberly reports to Leonard the death of his uncle. When she briefly goes to the bathroom, Sheldon mentions how fascinated he is with Leonard's mother.

In the cafeteria Howard and Raj also meet Leonard's mother, who has accompanied him to the University. When she goes to the toilet, the boys mock the fact that Leonard is apparently the least successful in his family. To deflect the conversation from himself, Leonard tells his mother about Raj's problem with speaking to women and Howard's living together with his mother. From that, Beverly concludes that they are both closet homosexuals.

When Leonard's mother and Sheldon go to a brain scan at the hospital, Leonard knocks at Penny's door. He advises her not to let herself taken in by her, but Penny believes that his mother is right in her belief that Penny had missed acknowledgement from her father. Leonard tells her about the "hugging machine" he built when he was 10 years old.

When Sheldon and Beverly come back, Sheldon confesses that he feels very comfortable in her presence. That amazes him to such an extent that they want to calculate it. Meanwhile Leonard and Penny drink tequila next door. Then they kiss each other. Soon they both land in bed. But when Leonard continues to discuss his childhood problems with Penny, she tosses him out.

In the apartment, Beverly and Sheldon have by now begun to sing karaoke.

Next day, Leonard and his mother bid each other goodbye at the apartment door. Penny comes out and goes down together with Beverly. But even before she has gone down, Penny starts to cry again, this time because of her mother. Beverly suggests that they continue the discussion in her office in New Jersey.