Why is the relationship between brother-in-law and aunt so subtle?

It has been said since ancient times that it is natural for a brother-in-law to beat an aunt. On this day, my sister took her husband back to the door. The husband was drunk at her husband's house and fell asleep on the kang. In my sleep, I stuffed the pillow into the bed and hung it in the air. Aunt saw it and went to help him. My brother-in-law grabbed my sister-in-law's clothes, and her sister-in-law broke free and ran away. My sister-in-law thought, I am kind enough to help you cushion your pillow, but you are so unreasonable. I must punish you. So, my sister-in-law wrote a poem on the wall and said, "You are kind enough to support the pillow, why are you pulling my clothes?" Don't look at your sister's face and tear it apart. Shameless! Lose face! "My brother-in-law saw it and wrote a poem next to this poem: drunk and sleepy, wake up late. Thought the good wife had arrived, but it was his aunt. Misunderstanding! Misunderstanding! After the mother-in-law came to see it, she said to herself, "Hey, hey, this is nothing! "He also casually wrote a poem on the wall: brother-in-law plays aunt, which is common in the world. If you don't catch one, it's cheap to run away.