In the common parlance of Wall Street, a "story stock" is one for which the numbers may not have arrived yet, but the narrative has -- and it's compelling enough to make investors buy essentially on spec. But from the perspective of Motley Fool co-founder David Gardner, every addition a Foolish investor makes to their portfolio has a story behind it, and on this week's episode of Rule Breaker Investing, he invites several of our analysts into the studio to share some of their favorites.But in this segment, he flies solo to talk about the Foolish pick of discount retailer Five Below (NASDAQ: FIVE).