definitely not a common as the stories, fantasies, and clips like to portray but i wouldn't say "rare." definitely a ticklish spot commonly with great reactions in the ticklish.
Pluto Guild and The Nylon Dungeon. I’m all for consensual in real life, but the darkness of fantasy is most satisfied by beautiful women mercilessly tickle tortured for the rest of there lives >:)
Not as a whole, but it’s decided into clips here... https://www.clips4sale.com/studio/33505/discount-tickling-clips-by-mtp-/Cat0-AllCategories/Page1/SortBy-bestmatch/Limit10/search/Courtney