He's like a 'flower monk' — he doesn't keep the monastic rules.
Tips
culture
花 ('flower') here refers to tattoos: Lu Zhishen covers his back with ink, hence the nickname. The term broadened beyond 《水浒传》 to mean any monk who breaks the rules — drinking alcohol, eating meat, chasing women — often affectionately rather than as condemnation.
usage
In modern colloquial Chinese, 花和尚 can tease any professional who publicly flouts the ethics of their role (a 'wayward monk' of politics, finance, etc.), though the 《水浒传》 reference remains the primary one.
