Normally I love being tickled; there is no "torture" component to it.
If there is any kind of tickling that I might consider torturous and worthy of fear, it would be on my back. I have a spot on my spine that is, oddly enough, sensitive to steady pressure. In the past people have tickled me there by wrapping both arms around me from behind and digging in with their chin. At first nothing happened, but ticklish discomfort built up steadily until after about 15 seconds I didn't know what to do with myself. They never kept it up longer than that (maybe because they didn't want to seem like sadistic ticklephiles?). However, I am guessing that if they continued, the slow buildup of ticklishness would not stop until I was completely, irrevokably insane.
If there is any kind of tickling that I might consider torturous and worthy of fear, it would be on my back. I have a spot on my spine that is, oddly enough, sensitive to steady pressure. In the past people have tickled me there by wrapping both arms around me from behind and digging in with their chin. At first nothing happened, but ticklish discomfort built up steadily until after about 15 seconds I didn't know what to do with myself. They never kept it up longer than that (maybe because they didn't want to seem like sadistic ticklephiles?). However, I am guessing that if they continued, the slow buildup of ticklishness would not stop until I was completely, irrevokably insane.