In the sultry heat of summer, Debbie and Diane, two busty, big-assed stepsisters, find an unconventional way to make money - selling homemade milk to horny neighbors. As they knock on doors, they encounter unexpected desires, with each customer hoping for more than just a glass of milk. The sisters, initially hesitant, can't help but feel the sexual tension building with each sale. Their final customer, a young man with a raging hard-on, pushes them over the edge, leading to a threesome filled with passionate kissing, intense fucking, and gallons of spilled milk.