When I was 15 I masturbated regularly and often to every form of porn I could get my hot little hands on, and occasionally made myself especially hard by watching myself in the mirror. Once I was watching myself in the mirror after reading a story about a guy's first blowjob (both giving and receiving) and had a sudden desire to experience the same.
My dick was hard, a full six inches, and when I bent my head towards it it was only about four inches from my mouth. I pushed my head with my left hand towards my dick and stretched my dick towards my mouth as hard as I could but still only gained an inch. I was fascinated by the sight of my swollen purple head so close to my eyes oozing pre-cum and felt myself getting close, but stopped jerking since I was determined to get it in my mouth.
I rested for a minute and looked around my room, and settled on what so many young men have done: I lay on the floor with the top of my head six inches or so from the wall, then swung my body up so that my feet rested on the wall. I then pushed until my rock-solid cock was just a couple of inches from my mouth, then slid a little until the tip was finally, finally brushing my lips. I opened my mouth and pushed harder and licked the head so it could slide in easily.
The taste of my precum was salty and bitter, and I was determined to get more of it. I thrust as hard as I could and my dick slid in until my lips were an inch down the shaft from the head. I just rested there licking my head and stroking my cock, amazed at the incredible feel of my first suck, and in less than a minute my dick stiffened to the hardest it had been until then, my head swelled hot and hard, and six massive spurts of hot cum shot into my mouth. The first three I swallowed, but as it made me choke the rest sprayed all over my neck.
As I lay there with a sore back and ribs, a little guilty at the taste of my cum still in my mouth, I stayed hard; I sat up and watched, now staring at my lap, now staring in the mirror, at my glorious, beautiful cock as my hand stroked it to another orgasm in just two minutes, two spurts that shot up my belly to my chest. While I only rarely sucked myself off after that, I frequently fantasized about it throughout my teenage years.