In the late 80s and early 90s there seemed to be an ongoing trend in many commercials: a group of kids are being bored to death by a stodgy old fuddy-duddy, then one of them breaks out some sugary snack and suddenly, it's party central.
This commercial for Sprinkled Chips Ahoy (do they even make those anymore?) is a classic example. You gotta love the generic rock music and hideous 1990 ensembles these kids are sporting. Anybody recognize the teacher? Bueller? Bueller?