A non-swear word. From an acting technique for crowd scenes. (Actors are given words to repeat to create the rumble of mob noises. Often phrases like apples and oranges, cheese and crackers, or in this case gromish, gromish, nater, gromish. Example: Oh, gromish, I forgot to pick up the dry cleaning.
GROMISH
Meaning of GROMISH in English
Slang English vocab. Английский сленговый словарь. 2012