I disagree with James that 'It's always kick/hit etc in X' where X= body part. With most body parts, 'in' or 'on' are actually both possible, but there's a difference: 'In' implies more force, suggesting that the blow crashed right into the body part in question; 'on' implies a lighter touch with little or no impact. For example, 'He punched me in the nose" suggests quite a violent and painful blow. If someone punches you in the nose, you're likely to end up with a nosebleed, bruising or worse. By contrast, a punch 'on the nose' could be just a friendly tap. A grandpa might punch his small grandson on the nose as a form of affection, for example. Just like if a fly lands on your nose or if you get a speck of dust on your nose, the contact is only on the surface. This, of course, is why we always use 'in' for shooting, because the bullet enters the body part. Compare, for example "He shot him in the shoulder" (entry wound into the flesh of the shoulder) with "He tapped him on the shoulder" ( a light touch on the surface). I hope that makes sense.

how about " shoulder"? in the shoulder?

thanks a lot

Hi Hasan, We use 'in' as the preposition for all of these. It's always 'kick in X' where X=body part. This is the same for the verbs 'punch', 'stab', 'hit' etc; they all use 'in'. I hope this helps Jimmy