Somehow, thanks to Bessie's mutant milk, your cock is cumming in reverse. Instead of squeezing out your seed, every contraction sucks milk from her monstrous teat embedded in your cock slit. Every twitch of your prong, every heartbeat driven alteration in hardness, seems to draw yet more milk from the seemingly limitless supply of her gargantuan udder. At first it feels like that fraction of a second before orgasm, that pleasurable fullness deep inside that would normally explode outwards. But now it's turned inwards and that volume inside you quickly fills with Bessie's milk.
Pressure inside builds only for a moment, and you shiver as you can feel her warm milk flowing down further into you. The maddening warmth seems to almost corkscrew inside your body before it flows into your balls. The myriad of tubules inside your sac fill quickly. The hot liquid Minotaur milk flowing into the labyrinthine tissues of your masculinity, quickly filling them to capacity. Its an odd feeling to be sure, like putting your nuts inside of a vacuum. Scrotum stretching as your serum bloated balls grow even heaver and denser with every gulp load of milk filling them to capacity. Your milk-filled boys, their tissues overburdened with liquid, jiggle like stiff gelatin assailed the onslaught of alien contractions. You begin to feel lightheaded as your traitorous cock continues to greedily suckle more milk.
With your reproductive tract seemingly heavy and full with milk, pressure builds again before you feel something slip. You shiver as you feel warm milk burning its way up into your bladder. The urgent worry you might burst, grows as your body slowly turns into a giant perverse water balloon full of Bessie's infernal udder juice.