What does the phrase "detained in the shed in advance" in Zhao Benshan's sketch "The Water Delivery Man" mean?

Metaphor is "ahead". In the northeast, it is impossible to plant crops outdoors in cold winter, but in greenhouses, that is, greenhouses, because conditions such as temperature can be controlled, it can be planted without weather restrictions, so that vegetables, fruits (including flowers) can be eaten in advance before the normal harvest season. Greenhouse (shed) is planted in the northeast, commonly known as "button greenhouse", because it looks like it is buckled on the ground from the outside! There is also this sentence "buckle the greenhouse in advance"! Gao and Zhao in the program are about the same age, so it can't be a mother-child relationship under normal circumstances. It is also a typical northeast humor to use this sentence to resolve the embarrassment of entering the door!