Tickling
Tickle torture consists of me restraining you completely and then tickling you until you use your safe word to make me stop. What more can I say? This is the least dangerous of any of the activities I engage in and thus just about anyone can experience it. It doesn't leave a mark, it only leaves you out of breath.
I can use my fingernails, feathers, and small implements like chop sticks to extract laughter from your tender, ticklish parts. This activity is only limited by our imaginations.