The TickleFoot device stimulates the most ticklish spots of the human foot – for women it was found to be the centre of the arch of the foot, while for men it is slightly closer to the toes. Researchers hope it could help beat stress by inducing uncontrolled laughter - https://www.newscientist.com/article/2312816-watch-a-foot-tickling-machine-discover-the-most-ticklish-spot-on-feet/ | New Scientist