How locked up men masturbate

Mr. MK's jerking off days were over as soon as we started with chastity. There's been a few periods where we took a few weeks off and he went right back to rubbing his little noodle. Now it's become so second nature that we don't take any time off and his chastity is pretty much permanent. I let him out about once a week to play with him. Sometimes he stays in longer. I let him cum once a month on the 1st but this year I've already cancelled January 1st and March 1st is unlikely. He'll be lucky to shoot 8 times by New Years.

I've decided to let him masturbate but he can only use a dildo in his ass and he has to stay locked, of course. I've read that it's possible to "milk" cum this way but if there's no stimulation to the penis, it's not an orgasm at all. I hope this is the case because I want him frustrated and denied the pleasure that he wants all the time, kind of like I get frustrated when he puts his pathetic thing inside me and can't last long enough to get me off. I'd love comments from anyone with experience with this who knows for sure. I fucked him with the dildo on Valentines Day and although he was moaning like a bitch, nothing came out of his little dick except some precum after we stopped.

It makes me laugh thinking about him fucking himself, moaning like a slut, trying to get a few drops out of his little weenie, even if doesn't give him relief.