Humiliation and Chastity
There are many other feelings associated with male chastity such as, intense sexual servitude, sacrifice, submission, slavery, etc. But chastity humiliation is right there along side with the rest of them.
His Keyholder may not be entirely aware of the heightened emotions swirling around inside the head of Her caged-up male. Her role is to keep his aroused male excitement at an excruciating high and agitated level.
And what better way than by mercilessly reminding him of his humiliating predicament…. one that he has chosen and that she has agreed to enthusiastically enforce.