Why are skeletons so calm?

Behind the Groan

Nothing Beneath the Surface

When something gets under your skin, it annoys or unsettles you. A skeleton has no skin for anything to get beneath, so the expression becomes physically impossible as well as emotionally descriptive. Keep the question relaxed and conversational. Put a small emphasis on “under their skin,” but do not rush to explain it; the familiar idiom should reveal its literal bony meaning on its own.