In the Flossenbrg concentration camp during World War II, a man witnessed Nazi prison guards perform tickle torture on a fellow inmate, followed by various other tortures which resulted in his death. They tickled their victim with goose feathers, on the soles of his feet, between his legs, in the armpits, and on other parts of his naked body. He broke out in a high-pitched laughter that very soon turned into a cry of pain.
In ancient Japan shikei, (private punishment) was reserved for those who committed crimes outside of the criminal code. One such torture was kusuguri-zeme, meaning "merciless tickling."
In the 19th and 20th centuries there were reports in the New York Times of restrained victims being tickled upon the bare soles of their feet, against their will and for the pleasure of their tormentors.
There are tens of thousands of nerve endings in your feet. The soles of the feet have a high concentration of Meissner's corpuscles, highly sensitive nerve receptors located close to the skin's surface.
