Some time ago I spilled a large cup of honey tea into my Model M keyboard, which unsurprisingly turned all sticky and wet and refused to work... So I brought it into the shower and gave it several good rinsings with hot water. I left it to dry for a couple of minutes, and here I am typing on it again. As an added bonus, all the bread crumbs, hairs and other oddities stuck between the keys were washed away by the water.
As has been said, these keyboards are indeed indestructible... Or, well, almost. This is actually my second model M. I killed my first with excessive, deliberate violence in an attempt to show how they were actually indestructible.