I was about 12 when I had my first time. Our farm had this hay-baling machine that was really old and made a hell of a lot of noise, but my family sold a lot of baled hay to local fairs and stuff (they don't use it to feed stock much anymore, it's more for decoration).
My older sisters always used to volunteer to run it, and I didn't understand why until after I had started to reach puberty. I was the last in my family to reach the rite of womanhood, and my sisters said that in the summer, they'd show me something special that helped 'ease the cramps.'
Well, when summer came, they said they'd take me out to the barn and bale hay. They said when the machine was on, you couldn't hear anyone, even if they shouted, so I had to do exactly what they showed me via gestures. They started up the machine, and it was God awful! I had to wear those huge ear protection headsets, like the kind they use in airports.
One of my sisters acted as a 'lookout' while the other sisters either worked the hay or moved the blocks off the belt. When the lookout said the coast was clear, two of my sisters set up this piece of smooth, rounded wood between the edge of the machine and a support crosspiece on the barn wall. Then they hoisted me up in the air so I was straddling the wood. My legs weren't long enough to reach the ground, so they held me in place to keep me from falling off.
Quickly, I realized that this piece of wood was heaven! It vibrated my whole pelvis though my overalls, and as I quickly slid back and forth to the vibration, I felt really good. I got very wet, and the lubrication of my undergarments across my clit sent a sensation that curled my toes and made me gasp.
The youngest of my older sisters unbuckled my overalls, and grasped my budding breasts. With the edges of her fingers, she pinched my nipples, and then guided my hands to do the same.
Soon, I came to my first orgasm, and it was a good thing my sisters were holding me up because I lost all control of my body. When I was done, they lifted me up, re-attached my overalls, and let me sit for a while. I watched two of my other sisters do the same thing. Both of them ground their crotch into the wood, rubbed their breasts, and screamed while they came.
We did this all summer, and I got tips and tricks to have multiple orgasms, plus access to their hidden stash of erotic literature. I did this every summer until I was 15, and my parents retired from baling hay.
To this day, the smell of a gasoline engine turns me on. Maybe that's why I ride a hog.