Soap in the Mouth

Did your parents do this to you?  Mine did.  It's not a usual practice at our nest, but when patience was short today and words we don't like to hear in our home were spoken, two of the nestlings got to hold soap in their mouth for a minute while they thought about their choice of words.  I realize "stupid" and "shut-up" aren't the worst words that could be spoken, but after they were repeatedly reminded and we heard those words over again and again something had to be done so the "nestlings" can learn to talk kindly to one another.

Junior High has been an interesting challenge, because sadly a lot of the students use foul language, so when "T" tells a sibling to "shut-up" and I reprimand him, he tells me he could use far worse words.  Anyone deal with this?  Is "shut-up" and calling someone "stupid" acceptable or not in your home?  What do you do when your kids use offensive words?