The Maternal Capacitance is the 15th episode of the 2nd season of The Big Bang Theory.
The episode's plot in a nutshell is that Leonard's mother (Beverly) comes for a visit and aside from Sheldon she makes everyone miserable.
- Berserk Button: When it seemed like Penny and Leonard are about to have sex, Leonard brings up how his mother would try to break them down psychologically by claiming neither of them were loved by anyone else before this point. Penny gets angry over Leonard mentioning her lack of sexual activity in the past, and kicks him out before they can advance any further in bed.
- The Bully: Beverly turns out to be a huge one, destroying other people's self-esteem unless they're accomplished scientists following cold logic and are arrogant just like her (she found Sheldon to be the only one like her).
- Commonality Connection: Beverly and Sheldon get along very well with each other and acknowledge it based on the fact that they're both very psychoanalytical and find themselves superior to everyone else, especially Leonard.
- Dreadful Musician: Raj. Penny complains it sounds like a cat, but then that makes her a hypocrite as both Leonard and Sheldon couldn't stand her singing back in "The Loobenfeld Decay"
- Drowning My Sorrows: Penny and Leonard get drunk to drown out the bullying Beverly inflicted on them.
- Early Installment Weirdness: Leonard claims that neither he nor Penny had intimacy before they start having sex in Penny's bed in this episode. Penny acts like he's right, but many later episodes establish that Penny's had multiple boyfriends or slept with men in the three digits.
- Kick Them While They're Down: Howard joins in on bullying Leonard with Beverly.
- The Dog Bites Back: Leonard then proudly tells Beverly that Howard still lives with his mom and Raj suffers from selective mutism so that he can't talk to women.
- Like Father, Unlike Son: Beverly and Leonard have nothing in common other than the fact they both wear glasses.
- Mistaken for Gay: Howard and Raj by Beverly.
- Too Much Information: Beverly keeps announcing "I have to urinate" to those who aren't eager to hear about it.
- First episode where Penny is seen in only her bra.