I used open ai chat gpt to get the answer. I tried google first, did not find a clear answer. Openai is unbelievable. But openai says “when vola of atm is larger than otm, buy higher vola and short lower vola” to lock the skew, I feel the common sense should be to short high vola at atm and buy otm vola. I am wrong?Eifert's Twitter thread is a solid explanation.