Plot summary
Kevin and his friends plan to sneak in to see the R-rated movie Carnal Knowledge with Ann-Margret, because it contains erotic scenes. Paul reveals that he will be having dinner with his mother's old college roommate and her college-age daughter Beth (Kawena Charlot) that night and can't make it. After Kevin, Ricky, and Chuck sneak in and subsequently get kicked out of the theater, Paul reveals his own "carnal knowledge" to Kevin when he tells him he had his first sexual encounter with Beth, leaving him confused at exactly what happened.
At first Kevin is upset when Paul doesn't disclose any details, then he inadvertently reveals Paul's secret to his friends. However, when Paul confesses he can't cope with a casual relationship, Kevin helps out and accompanies him to the airport to say goodbye to Beth. Even though Paul didn't have the chance to meet Beth there before she boarded the plane (he thought he did see her through the plane window, however), he still appreciates Kevin, his long-time best friend, who'll do anything for him
Credits
Adapted from Wikipedia contributors, The Wonder Years season 5. HTML formatting and reference markers removed.