also: むしのよい
expression, i-adjective (yoi/ii class)
selfish; self-serving; conveniently self-centered
Describes a person or attitude that is selfishly convenient for oneself, often ignoring others' needs. Frequently used in the phrase 虫のいい話 (a self-serving story/proposal).
See also: 虫がいい
彼の虫のいい考えには呆れてしまった。
I was amazed at his selfish way of thinking.
そんな虫のいい話があるわけない。
There's no way such a self-serving story could be true.
Synonymous expression; 虫のいい is more common as a prenominal modifier, while 虫がいい often appears in predicate position.
The phrase 虫のいい literally means 'the insect is good,' but the exact origin is uncertain. It may derive from the traditional belief that a 'bug' (虫) in the body influences one's temperament, so having a 'good bug' implies a self-indulgent nature.