I am a ticklee, so I would answer about what I like about being tickled.
First things first, a lot of ticklers are into tying down a ticklee and tickling her helplessly, which I am mostly not into. I am a very cooperative ticklee, so during a session, the tickler just has to let me know which spot he plans to tickle, and I would be helping him pin down the spot totally vulnerable. I do like the tickling to be a bit tormenting and relentless, but not beyond a point at one point.
Single finger twitchy tickles work best on me, though I do let a tickler use an electric toothbrush or a hairbrush on my bare feet sometimes because feet are one spot where the tickler can get a bit rough with. I like wiggly pokes at the sides, and being pinned down and getting it good over my bare belly and underarms too. Underarms are my most ticklish areas so even a finger touching their centres feels tickly.
What I like about being tickled is how it makes me laugh uncontrollably and the feeling of being dominated by the tickler, which is a big turn on for me. I like it when during a session, a tickler gets my spots over and over repeatedly until he is highly turned on and that leads to some good hard sex.
