The most ticklish spot on a man are the soles of the mans feet and the mans armpits.
The ribs, neck and stomach are also the most ticklish spots for a man.
The most sensitive part to tickle is the feet as well as the stomach, ribcage, neck and the underarms.
These areas of the body are the most sensitive parts to tickle because they are known for their high concentration of nerve endings, and especially the ones sensitive to light touch which can trigger the tickle response.
Also if you try to tickle yourself your brain won't let you feel the tickling sensation.
The part of the brain that does not allow you to tickle yourself is your cerebellum.
The cerebellum is located at the back of your brain and is the primary brain region which is responsible for preventing you from tickling yourself.
The cerebellum monitors your movements and predicts any sensory consequences of your actions.
And by doing so it cancels out the tickle sensation when you initiate the tickle yourself.
Your brain knows to expect the tickle and so it doesn't allow you to feel the tickle when you've done so yourself.
Basically when you move your own hand to tickle yourself, your cerebellum anticipates the touch of the tickle and the resulting sensation.
The prediction of the tickle allows your brain to suppress the tickle response which makes the tickle sensation less intense or even absence.
Your cerebellum distinguishes between external touch such as when someone else tickles you and the self generated touch is prevented when tickling yourself.
Also the somatosensory cortex that processes touch and other sensory information, is also involved in the tickle response although it's activity is reduced when the cerebellum predicts a touch that is self generated.
The ticklishness is also influenced by factors such as context and mood, with situations of fear or anxiety being able to suppressing the tickle response.