i have found it extremely difficult to be stupid with iodine. the closest i came was putting about 100 grams of KI in my bath water. it is amazing how much of what is in the water is absorbed by the skin. i got a huge headache that lasted a couple of days. it was real similar to taking five grams internally all at once, although the oral dose was more intense in other ways, like it made me jittery.
just consider the dose youre used to and the tissues involved and i believe one could use KI anywhere in any orifice, given the concentration was proper.