Why does the ass hurt after drinking Jianpi wine?

..... my ass hurts after drinking. It comes from a joke.

The joke is this: The wolf is greedy for the beauty of the white rabbit, and plans to invite the white rabbit to drink at night, and then defile it, so he invites the white rabbit, "White rabbit, shall we have a beer at night?" The white rabbit readily agreed, but in the evening, when the white rabbit was as drunk as a fiddler and completely unconscious, the wolf's trick also succeeded. The wolf thinks it's so easy to get it. Why not invite the white rabbit for a beer at night? So I am very happy to invite the white rabbit again. As a result, the little white rabbit refused him this time and said, "I won't go today." My ass hurts after drinking beer. " 、、、

It is such a moral,,,,