Tickling my feet whether it's fingers or any tickling tool drives me wild with laughter and when I laugh it is a constant contagious deep belly laugh .. Depending on the Ler,and the situation I am being tickled,I howl with laughter and squeal ..
Someone can touch my soles or my toes with a light touch and my reactions are instant ,and I can't hold it in..
Paracarl44! That happened to me at last years Nest at one of the workshops titled " Massage and Reflexology" . I intended on watching the demonstration and due to certain happenings,I happened to be the one picked to be the one demonstrated LOL..
There is a thread somewhere around here talking about it ,when Mkeemer put me on a massage table,had me lie down and using a technique with his fingers attempted to show where the lines on the foot control certain body parts ,and I laughed even though Mkeemer wasn't intending to tickle but he knew it did

My laughter got constant,and then a pen was brought out to reflect where the lines were for the observers for the class and I couldn't stay still LOL. They played Tic Tac Toe on my ticklish soles and everyone was laughing,enjoying the class ,not feeling sorry for me hahahhhaha,....and I loved every minute ..Whew!,thank gawd they didn't take a brush ,towel and scrub em clean

That would have been even worse!
So yes writing on the feet is torture especially as extreme ticklish as mine