Kobold Breakers: Worship from inside
With a piston going back to a control box of some kind.
Mordenkainen's Magical Machine
"initiate penetration piston!"
[yiff] Cerberus Journal - two third
His pistoning went on, and more of the cruel juice welled up within us. this cursed warhound had the nerve to actually pump his essence into us!
A Night In New York - Part One
Soon shifting his legs as he pistons into the leopard's muzzle. the suckles and tugging from the texture made it slightly difficult, but his main concern were those deadly fangs.
Chapter 03 - Freshening Up
His fist connected with the piston, turning it into a thousand separate pieces of shrapnel that shredded nearly everything in the test chamber.
A Break from Maintenance
As if sensing his desire, and on cue, the program ramped up, the pistoning of the shaft within him growing faster, harder, and more brutal by the second.
K-495 (chapter 2)
"i think there's a broken piston," he chuckled," yep, found it here!" he said, rubbing the grease off his paw onto his shirt. he took out some tools and went to work, dismantling this part of the engine, to get at the broken piston.
This Is How It Feels
She started pistoning her glans through his sphincter while arching it upwards within his prostatic urethra, prodding and stretching the flexible walls which caused him extreme stimulation.
An Anthro's Tale-Chapter 3-All American GTO
They also reduce friction and inertia,and make the engine more responsive.the pistons compress the air-fuel mixture in the combustion chamber and convert the heat energy into mechanical energy.
Placating the skipper
"and this unassembled piston serves as visual confirmation that this soldier-human male is of exclusive non-grammatical gender that is not child-bearing."
Bunny Love: Chapter 4
Once 3 of the four inches were inside her, rose began to piston it in and out of her tailhole, while still rubbing her clit and watching blake.
A Scent Seduction Short: Jenda
Just when jenda thought she couldn't get any more excited a second piston driven cock came into view , glistening with lube and pressing against kara's tail hole.