How good is the eldest sister-in-law, the next sentence

The next sentence is where eldest sister-in-law is good, and eldest brother knows best.

This is the next classic sentence. I think this sentence is quite funny, which is also a philosophy! Eldest brother is not good, and eldest sister-in-law knows best. Isn't that what it is? After all, two people live together and know each other. The first time I saw this sentence on the network video, I thought it was a derogatory term at first, but later I learned that the new society and new ideas have also triggered many new words. We must understand and accept it slowly, or we will be eliminated by society! I hope I can help you!