After a powerful magical "accident," the town formally known as Ponyville is now called "Slutville." This might have something to do with the entire adult female population being turned into big-tittied, smoking hot bimbos. With the problem of the ratio of females to males still being three to one, six of the hottest bimbos decide to open their own booths at The Annual Harvest Fair.

For...charitable reasons.

It's as good a reason as any to get more dick than any of the other sluts.