I heard of an oyster wash once about three years ago and have never seen a recipe for it. Now I know why, it is associated with a different term.
Oysters on the Half Shell with Hog Wash
From EatingWell: May/June 2011
It may seems a little intimidating to open an oyster, but after a little practice it gets easier. In this recipe, the oysters are served with a spiced-up, California-style version of mignonette sauce inspired by the folks at Hog Island Oyster Company on Tomales Bay in Northern California.