をいいことに

also: をよいことに

Meanings

taking advantage of ...; using ... as an excuse

usually written using kana alone

Used to indicate that someone exploits a situation, often with a negative connotation. The preceding noun or clause describes the favorable circumstance being taken advantage of.

彼かれは上じょう司しが不ふ在ざいなのをいい事ことに、早そう退たいした。
Taking advantage of his boss's absence, he left work early.
親おやが甘あまいのをいい事ことに、子こ供どもは何なんでも買かってもらえると思おもっている。
Taking advantage of their parents' leniency, the children think they can get anything they want.