Dressed in latex and boots, Miss Medea and I are going to use urethral sounds to fuck the cock of our sub. He's in the sling, ready for his urethra to be penetrated by us. First we each take a dilator and and take turns to put it into his dick, watching the metal move up and down inside him. Then it's time to stretch out his cock a bit further and Medea and I give him a double urethral sounding. After moving up to a bigger size, it seems our sub is enjoying us fucking his peehole by sliding metal rods down his cock a little too much, so we decide to lock him up. I introduce Miss Medea to a lockable device that fits down his urethra meaning he will be unable to masturbate or orgasm. It's a devilish tool and also a little painful if you are aroused, but that's not our problem... We lube him up, insert the metal rod, secure the device and lock the padlock shut. There's one key for each Mistress, but who knows when we will let him out of this chastity?