When I was around 14, I had a friend, Kevin, and we would wrestle all the time. The wrestling was sometimes real, but more often theatrical. We would get each other into a hold, then throw each other across the room (his bed was in the middle of the room, so we'd throw one another onto the bed, then we'd bounced off the bed to the other side of the room).
One weekend-night, his parents and sister were gone, and we started wrestling as usual. He threw me onto his bed, and I bounced off onto the floor on the opposite side. Then he followed by rolling off of the bed onto my back. He grappled with me for a bit, trying to get me in a full-nelson head-lock. After a little while, I felt something hard and warm pressing against my lower back and upper butt through my clothes. I was instantly turned on, not quite believing what I felt pressing against me. I pretended to struggle for a little while, making sure to rub his shaft with my body. As we wrestled, I'd stick out my butt, back and forth, and I noticed the involuntary twitches from his penis.
After a while, we stopped our pretense of wrestling, and just rocked back and forth, with his erect shaft pressing against my butt and lower back. Then, I reached back and pulled my shorts to my knees, and he did the same. We both wore white briefs, and both of our dicks were pressing against the fabric. I noticed the tip of his penis actually peeking out over the top of his waistband.
I felt really weird and really exhilarated. We didn't intend to arouse each other, and both of us are Mormon, so masturbation and especially arousing somebody else, and ESPECIALLY arousing somebody else of the same sex are definitely prohibited. But we were both extremely horny teens, we were caught up in the moment, and I didn't really consider or pay much attention to the morality of what I was doing.
Stripped to our underwear, I jumped on him and started wrestling again. I bear-hugged him from behind, not-accidentally pressing my shaft against his butt, and threw him onto the bed. He turned onto his back, and I jumped on his stomach, so my butt and balls rubbed against his shaft. We kind of pretended that I was trying to pin his shoulders to the bed, which was the usual goal of our wrestling matches, but we were really just rubbing each other.
His hard penis pressed from near my butt hole to my balls, and as I rubbed back and forth, I saw the head of his penis sticking out of his underwear. It was swollen and purple, and I really wanted to reach down and touch it with my hand, but I didn't dare. After about a minute, I swear my vision started to dim as I felt my groin begin to pulse and throb. I pulled down my waistband, stroked my penis twice, and ejaculated into my hands, onto his belly a little, and onto the bed a little. He bucked me off of him and before he even got a hand on his penis, he squirted all the way up his stomach and chest and got a couple of drops on his lips and face. We laughed and panted for a bit, then got towels to clean up before his parents and sister came home.
We never really masturbated together again. Sometimes after he turned off the light and after our late-night conversations wound down (I always slept over at his house, 'cause I have way too many siblings to have any privacy, and he had cooler games), I could hear motion on his bed, and I knew he was masturbating, and I would rub my own penis against the ground, which is how I often masturbated back then. But we never did anything together like the night we wrestled in our underwear.