There's no fighting the appliance of science.

God, how is a brute wanking machine like this giving you such a good 'hand job'? It's the pressure, the sheath that's gripping you inside squeezing your shaft and your head almost too tight but not quite. It slides up and down and squeezes the base of your cock, then just behind your helmet, not too tight, not too fast, just... fucking perfect. It's warm and wet and somehow the knowledge that this is a machine that will never tire, whose speed will never alter, turns you on a little more. It makes your task all the more difficult.

The tech-girl stands up and pulls her chair over so she can sit and watch you. But you're starting to get your muscles back now, and she jumps in alarm as you raise first one hand, then the other, and move them to your lap.

"You're a quick healer, mister," she smiles, "but your cock and balls will come off before that thing does. It's very, very secure."

Screw her, she's probably bluffing you think as the sensations returning all over your body make your prick feel bigger and better by the second. Normal pleasure signals from your cock, being jerked, tugged and squeezed in a damnably smooth, sweet rhythm start to filter into your head, and you feel your balls twitch and leap in their little cup. You get your hands on the tube and start tugging.

Your muscles are getting stronger too, and before long you can sit up more and your hunching over, scrabbling at the airtight seal and trying anything to get the damn jerk-off machine off your precious package. And all the while the unstoppable lubed jerking keeps driving your pulse and your pleasure up and up and up. You glance at the transparent end, and see the lube-slick head of your prick is starting to look a little creamier with your pre-cum. God, it feels good. So good. She got you, this girl, she trapped you and now she's not even going to use her body to get you off. What a way to lose.