Originally Posted by indian_cpl2013
not sure how?
I would think a ring gag would be an ideal start. Whomever it's intended for has their mouth opened, then insert a dildo into the opening.
So I picture it as - the sub tied, their mouth forced open with the ring gag. The dom is able to push the dildo through the ring to initiate the gag reflex, yet be able to pull the dildo back.
Another thought, same rig but once you've determined the proper depth punch a whole through the shaft of the dildo and tie it with a leather thong to the ring.
My suggestion would be to get an anatomically correct dildo, one that has testicles - for a pleasing visual effect.