Note: The listed episode synopsis is from Napoleon Dynamite and has nothing to do with the episode. The synopsis below is from Aceshowbiz.com.
Marge and Lisa's mother-daughter Valentine's Day plans take a turn when Lisa meets Nick (guest voice Michael Cera), an intellectual romantic who shares the same passion for culture, history and literature. Lisa and Nick fall head over heels for each other in a fairytale romance and make a secret getaway to Mulberry Island to profess their eternal love. Meanwhile, Bart and Milhouse are inspired by the hosts of "MythCrackers" (guest voices Jamie Hyneman and Adam Savage) to "crack" Springfield Elementary's own legends.