expression, i-adjective
irritable; in a bad mood; cranky
Idiomatic expression describing someone's foul mood, as if a bug inside them is unsettled. Often used when someone is touchy or easily angered for no clear reason.
今日は上司の虫の居所が悪いみたいで、みんなピリピリしている。
The boss seems to be in a bad mood today, so everyone is on edge.
虫
If you talk to him when he's irritable, you might get yelled at.