Its a holiday on the second Sunday of June. Its when men decorate there Grunskins with paint and glitter in honor of that body part. In tradition a man is suppose to have a woman lick it 14 times before painting.
Faces made of a single pile of sand. Pebbles, shells, sticks and seaweed are used to define facial features such as nose, eyes, mouth, ears, etc. Grunkies are meant to be a little grotesque. They are said to keep watch over swimmers and protect them from dangers, such as the undertoad.
Derives from Sydney Rhyming slang, "Reg Grundies = Undies", which is a reference to that excellent Australian TV production outfit Reg Grundy, behind such televisual classics as Neighbours, Home and Away, The Sullivans, etc.
From "The 12th Man Again", wherein commentator Max "Tangles" Walker discusses the perils of prolonged bouts of commentating on international cricket competitions:
"when you're sitting around in the commentary box for this length of time, it's not unusual, really, for the old cods to maybe nod off, get a bit numb; I think the best thing to do in situations like this is to get up, stretch the old legs; maybe even try to casually slip the old hand down and, maybe, give them a bit of a rub; probably try and adjust the old reg grundies while you're down there; try and loosen them up a bit. Anything, really, to try to get the old circulation going again."