McGrunchies Posted in M Best definition McGrunchies Diarrhea;softened stool or when you have the bubble guts. Often contains corn, but not always. Oh no, I got the “McGrunchies”; I just “McGrunchied” sharted in my Pants! How satisfied are you with the definition? Looking for McGrunchies meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 40 times.