Rule: Your main purpose is to be a mouth fuckhole. Your other holes are merely for punishment. As a result your pussy will receive no pleasure while serving.
The easiest way for Sir to enforce this rule is to make sure my pussy is locked up tightly in a chastity belt anytime he wants to use me. Being belted reinforces that my pussy will not be getting any attention while serving, which results in an eager mouth and ultimately makes me more useful to Sir as a mouth fuckhole. :)
I recently had my Fancy Steel belt updated with a leather lining and some super cute hello kitty engraving so I was without it for several weeks.. Thankfully, I have several other belts and options for keeping my pesky hands away from my greedy pussy while I waited.
As soon as I got my belt back Sir wanted to check it’s effectiveness, so I was allowed to play with the hitachi after I was locked in. As predicted, the hitachi was completely useless and I felt almost nothing through the metal shield. This lead to lots of frustration and pouty faces, and then to the desired result of wanting to be useful and suck. :)