Here's a fantasy of mine. I have my sissy locked into a chastity belt, with no rear guard, and underneath the chastity belt is this.
What is it?
It's a silicone butt plug attached to a cock ring.
The chastity belt would make it impossible to remove the cock ring, and my sissy would be plugged any time she didn't want a used butt plug hanging between their legs, or put another way, when she isn't making number 2 or being used roughly by her master.
This is the only solution I can think of to the 'locked in a butt plug but has to go to work problem."
This way, when not in the bathroom, there is no place to put the plug but where it belongs, in the girl's butt, but she can go to the bathroom when she needs to, without being unlocked by the Master.
What do my sissies have to say about that? I think it's a wonderful idea, and I wish I could be in the same city as my sissies so I could personally administer its implementation. I would put the ring on the sissy. I would insert the plug. I would lock on the chastity belt. I would keep the only key. Does anyone want to try it!?