Far from it, isabeau. Tickling is simply one of those fetishes that (for reasons unknown) doesn't seem to get written about very often in BDSM fiction. I imagine part of the reason may well be the laughter factor. Dungeons traditionally (stereotypically) are places of pain and tears and so laughter could appear incongruous in that setting. However, a hard tickling session can be every bit as torturous as a hard flogging except, rather than result in pain, its results manifest more on an emotional level -- the humiliation of peeing one's pants and laughing at the same time, for example. To describe such things in writing isn't an easy task to do well, even when you can write from experience.