''Young People Fucking'' intertwines the stories of four couples and one threesome as they have one sexual encounter each, which are divided into chapters: prelude, foreplay, sex, interlude, orgasm and afterglow. Each couple represents a specific relationship archetype. The first of the five is called ''The Best Friends'' because the characters, Matt and Kristen, decide to become Casual sex. Their 20-year friendship initially makes this awkward because they know everything about each other – except that they each secretly knew the other once had romantic feelings for them. These feelings are rediscovered and acknowledged as they become intimate.