receiving corporal punishment is a major psycho-physical experience, more so if it is infrequent and given in ceremonial fashion (going to a special place, bending over, removing clothes, etc.). It is quite capable of being both humiliating and painful on the one hand, and a sexual stimulant on the other. The experience impregnates itself in the memory and is re-lived in these forums often in fantasized forms.
Few enjoy hard corporal punishment at the point of administration; the thrill occurs in the anticipation and the re-call of the caning experience. It could hardly be otherwise. Yet for these thrills to be real caning actually has to happen.