Grub Share definition Flag Australian slang for idiot, asshole, dickhead or moron. Can be used in video games when someone steals your loot or steals your kills You stole my kill, you dirty grub! Come revive me you absolute grub! You dirty grub, you took all the ammo!!! Grub by 1UP_Pubg January 1, 2021 Get the Grub mug.