What is the fourth tickle spot that is not in the top three when you hear about tickling

When discussing tickling, the most commonly mentioned spots are typically the feet, sides, and underarms. While there isn’t a definitive "fourth spot" universally recognized, another common area that many people find ticklish is the stomach. The sensitivity of ticklish spots can vary from person to person, so others might experience tickling sensations in areas like the neck, back, or ribs as well.