Determined to teach his son how to behave more like a grown up, Dad forces Dennis to accompany him to his school reunion party. Dad dresses in traditional school uniform as per the invitation's instructions, but he has been tricked by Walter's dad—all the other guests are in formal party wear. Outraged that Dad has been humiliated, Dennis urges him to take action. Joining forces in their revenge, Dennis discovers Dad has a prankster side he has never seen before, as his father shows everyone who the real menace of Beanotown School is.