noun
good-for-nothing; idler; freeloader
Derogatory term for a person who does no useful work and lives off others; literally 'waste-rice eater'.
あいつはただの無駄飯食らいだ。
That guy is just a freeloader.
無駄飯食らいと言われないように、ちゃんと働け。
Work properly so you won't be called a good-for-nothing.
Compound of 無駄 (waste) + 飯 (meal) + 食らい (eating, from 食らう 'to eat'). The image is of someone who eats meals without doing any productive work.