This story happened two years ago, a day I'll never forget. My dad and I still service each other, especially when we go camping. It's awesome and the orgasms are great, with tons of cum!
After a fourth-of-July celebration, my dad and I headed back to the house to get to sleep. On the way home my dad stopped at a rest stop to go to the restroom. He went in and after a few minutes wondering where he was, I decided to go in to see what he was doing. I walked into the empty restroom where I heard grunts coming from the stall nearest the wall. I walked in front of the stall where I saw my dad beating away at his meat, his cock flailing around.
Normally I never think about guys when I masturbate, let alone my dad, but I found myself ripping the seams of my pants with an instant hard-on at the sight of my dad's eight-inch cock. He told me to take the stall next to him and he'd teach me a few things. I walked into the next stall, now realizing that there was a large hole in the wall, bigger than a glory hole and right at hip level. I pulled down my pants and let my seven and a half-inch cock stand straight into the air.
I suddenly saw my dad's hand reach over and begin stroking my cock. I wanted to ask him what he was doing, but it felt so good that I reached my hand over to his stall and began to stroke his cock as well. We both came in about 10 minutes, exploding onto each other's chest.
After cleaning up we walked back to the car, where I serviced my dad one last time, as his cock budged through his tight jeans. When we arrived home my dad and I went to the restroom, where my dad told me that we'd have to do that again, saying that I really knew how to stroke it. We went to sleep, with me tossing and turning, thinking of the feeling caused by the orgasm at the rest stop.