You Vegetabelieve It! is the third part of the 26th episode of the second season in Dexter's Laboratory. In this episode, Dexter gives Dee Dee a growth formula that causes plants to grow to an enormous size. However, Dee Dee uses up all of the growth formula in the backyard, causing all of the plants to come to life, literally. With her brother's help, Dee Dee destroys every living plant.
The scene where Dad is buried in the backyard begging to be fed is a reference to the musical and film Little Shop of Horrors where its main villain Audrey II is a carnivorous plant who is always begging to be fed. Dad even speaks in a similar tone to the deadly plant.