Gyeongseong Ilbo (Keijo Nippo), July 8, 1942
Saying “Aigo” also results in punishment
Seodaemun Police Officer Suggests a New Idea for Regular Use of Japanese Language
At the Seodaemun Police Station, Chief Yoshioka had been encouraging his staff to use the Japanese language in public and private life. On June 26, Detective Sergeant Hirayama came up with an ingenious idea and put it into practice as a model for others to follow, achieving very good results ahead of the other police stations in Seoul.
In short, it was decided that if anyone unintentionally used Korean or English while working in the station, even if it was just a word, they would be charged 10 sen each time.
Korean and Japanese employees used to exchange unpleasant words such as “aigo” and “nappeun” in Korean and “service” and “slogan” in English. But since then, these impure words have been cleanly eradicated as a result. The accumulated fines will be used as donations for the National Defense Fund.
Reddit Link: In Japan-occupied Korea, Koreans often mixed their spoken Japanese with Korean words like 아이고 (‘gosh’) and 나쁜 (‘bad’) and English words like ‘slogan’ and ‘service’ – in 1942, one Seoul police station cracked down on this by fining employees every time they uttered a Korean or English word : korea (reddit.com)