Feet are ticklish because the soles of your feet are sensitive to touch. Other commonly ticklish areas include the armpits, sides of the torso, neck, knee, midriff, navel, and the ribs. No record of this being a result of stress.
The human body is the entire structure of a human organism and comprises a head, neck, torso, two arms and two legs. By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life. These cells are organised biologically to eventually form the whole body.
An erogenous zone (from Greek ἔρως eros "love" and English -genous "producing" from Greek -γενής -genes "born") is an area of the human body that has heightened sensitivity, the stimulation of which may result in the production of sexual fantasies, sexual arousal and orgasm.
People have erogenous zones all over their bodies, but which areas are more sensitive than others vary. Some may resent stimulation that others find arousing. The stimulation of these areas can produce gentle, mild or intense arousal.
Navel fetishism, or belly button fetishism is a partialism in which an individual is sexually attracted to the human navel. In an article published in the 1975 issue of The Psychoanalytic Quarterly, psychiatrist Gert Heilbrunn specified that a sexual partialism for navels is a subtype of fetishism in which an individual displays a lifelong erotic preoccupation with the navel which is an non-reproductive body part.