What word or phrase does your mother always say?
Old English grunnettan "to grunt," frequentative of grunian "to grunt," probably imitative (cf. Danish grynte, Old High German grunnizon, German grunzen "to grunt," Latin grunnire "to grunt"). Related: Grunted; grunting.
1550s, from grunt (v.); as a type of fish, from 1713; meaning "infantry soldier" emerged in U.S. military slang during Vietnam War (first recorded in print 1969); used since 1900 of various low-level workers. Grunt work first recorded 1977.