A monk and xiucai

There were countless jokes about xiucai 秀才, here is one of them. I don't know the origin of the derogatory term 秃驴 for monks.

一日，秀才行路遇一和尚，秀才问：“师傅，请教秃驴的秃字怎么写？” 和尚答：“秀才的秀字歪歪屁股就成了！”

One day, a scholar met a monk on the road, "Shifu," the scholar asked, can you please tell me how to write the word tu 秃(as in bald donkey)?" "Just wiggle your butt," the monk replied.