>>86028
To add on to this: depending on the scenario, a look of desperation as if pleading for help towards someone (even if no one's there), a vacant look (if they've given in), or extreme fear. Usually this is expressed in the eyes. It all contrasts with the mouth, which is open usually in a forced smiling laugh or scream. That sort of dissonance, done just right, can imply an unnerving quality that speaks to the intensity of the situation. Add in sweat and/or the sight of muscles straining to compliment it, if the full body's in the pic.
Aiming towards making the tickling something you can "feel" just by looking at it really drives it home too, as opposed to just seeing it as an outside observer. Don't know enough about art to say exactly how to do this, but there's just this quality in some art where you can really feel the softness of brushes on skin or the intensity of a soft feather flicking right on a sensitive spot. It's overhwhelming to look at.