Marshall finds a possible band for the wedding, The 88, but Lily will not approve the booking until she hears them play "their" song ("Good Feeling" by Violent Femmes). The only way Lily can hear them is if she sneaks into a high school prom where they are playing. Lily thus decides to sneak in with Robin and Barney. Robin is excited, because she never had the chance to attend her prom in high school, having been too busy with field hockey tournaments. This is later assumed to be a lie as Robin had yet to reveal her past as Robin Sparkles. When they arrive, they find tight security, so Lily and Robin offer to be the dates of two nerdy high school seniors, while Barney decides to find another way in.