àm-káu暗九

a custom or superstition where it is believed

a custom or superstition where it is believed that bad luck or misfortune comes at an unlucky age where both digits can be added to result into a nine (9), especially at a ripe old age (e.g. 90, 81, 72, 63, 54, 45, 36, 27, 18, 9, etc.)

English Wiktionary, “暗九” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E6%9A%97%E4%B9%9D · confidence: Medium