Penny and Aggie/Recap/Modern Maturity

"You can put aside what you think are "childish" relationships, and take years to realize your error. You can discover that the best path to mature emotional balance is going out and getting crazy for a while."

Penny's mom Lynda devotes one of her columns for a parenting website to the problem of how to tell when one's teenager has matured. In the process of writing it, she recalls how she and Rob met as adolescents back in 1980. Rob, then a smart-alecky jock, became interested in Lynda after she put him and his friends in their place with a withering stare for mocking her nerdiness. He proceeded to flirt with her through a series of childish pranks, to which she'd respond with anger and even violence.

However, Rob showed Lynda he could be sensitive and thoughtful when he not only agreed to lay off his pranking for a few days when her grandfather became ill, but sent a Star Wars-themed "get well" card. This laid the foundation for their eventually falling in love. Present-day Lynda concludes her column with an insight gained from her relationship with her high school sweetheart (see page quote).

Rob, when told the column's subject, is skeptical that their daughter has matured. Lynda argues that Penny's grown up a lot since running off with Rich the previous spring. Just then, however, they hear Penny shouting from upstairs, "Oh my God! What are you doing in my bed?", causing Rob to have doubts once again.

Tropes

 * Cannot Spit It Out: A non-verbal example here, second and third panels.
 * Cliff Hanger
 * Deadpan Snarker: Rob, in response to Lynda's suggestion that they start looking into colleges with Penny, and to Penny's outburst immediately following, says, "Or penitentiaries. One of those."
 * Death Glare: Lynda uses this to stop Rob and his friends from taunting her with "Nerd alert!" (In the strip itself, the look receives the Unsound Effect "MEDUSA STARE," and in fact metaphorically turns the boys temporarily to stone.) Subverted in that Rob becomes attracted to her as a result.
 * Flowery Insults: When Rob snatches her copy of Carl Sagan's Cosmos out of her hand, Lynda calls him "you ambulatory primordial soup!"
 * Gone Swimming, Clothes Stolen: Lynda takes two friends skinny-dipping in order to teach them to celebrate their bodies, free of the "repressive male patriarchy." Her lesson backfires when Rob and his friend Henry steal their clothes, whereupon one girl fears she'll "turn lesbo" after spending too much time naked with girls, while the other is turned on by the possibility that Rob was checking out her breasts.
 * Jerk with a Heart of Gold: Rob.
 * Longing Look: Rob and Lynda exchange one while dancing with other people at their prom.
 * Nerds Are Sexy: Specifically, teenage Rob finds Lynda's feistiness attractive.
 * Shout-Out: The arc takes its name from the former title of AARP The Magazine.
 * Soapbox Sadie
 * Stuffed Into a Trashcan: Lynda does this to Rob after he pranks her one too many times.
 * Tsundere (Type A): Lynda starts out antagonistic and angry, even violent, towards Rob and only later develops tender feelings for him. Justified, given that Rob initially shows affection by pranking her relentlessly.
 * Unishment: When Rob grabs her copy of Cosmos, Lynda jumps him and grabs it back. While still astride him, she leans forward threateningly and says, "Let this be a lesson to you." Rob, looking down her halter top, says, "Oh, yeah. I sure wouldn't want to repeat this experience," causing her to run off in disgust.
 * Whole-Episode Flashback