This happened in 1976. Well before a horny teenager could easily access hardcore porn. Especially in a small very conservative town.

I was sixteen and standing at the magazine rack of the local truck stop looking at Penthouse and Hustler, when an older guy walked up. He was someone I knew as a customer at the gas station where I worked.  He started up a conversation and told me that he had some much better magazines in his car and I could take a look if I wanted to.  Naturally I said yes.

I was on the passenger side, flipping through my first true hardcore magazine, when he asked if I liked what I saw. I'm sure I said yes. But I didn't need to; the bulge in my pants did it for me. He said something like "I can tell" and reached for my crotch and started rubbing. I kept looking at pictures while he rubbed my cock through my pants. When he started to open my belt I helped him free my cock. After a few minutes of stoking me, he wanted to push my pants down, and I help him with that too. He then leaned over the seat and started sucking my cock. After sucking me for a while he leaned back and said "that wasn't your first time for that, was it". I said no it wasn't, and reached for his belt. We pushed his pants down, and I leaned over and sucked his cock. When I stopped he said "that wasn't your first time for that either."  I had sucked and been sucked by three other guys before this day. The lucky pervert had found himself a young but already experienced cocksucker when he lured me to his car with porn.  

We decided to we should get out of the truck stop parking lot, so we drove to a spot in the woods and continued to suck each other's cocks in the car. He was the first guy to let me cum in his mouth. I wasn't ready for that yet, but we continued to get together and eventually I was swallowing his cum too.

He lived alone and had a great porn collection (including the old super 8 loops) so I ended up at his place a lot. At the time I was dating (and trying to fuck) girls. He loved it when I would show up at his place all horned up after a date that didn't go "all the way". It didn't take much before I would fill his mouth with cum.  He would also hang out at the gas station when I was working. We would go to the back room and trade blow jobs with one of us on his knees sucking the other. Many times a customer would pull in and I would need to stuff my hard cock back in my pants and get out there. I often wondered if anyone noticed the bulge. (Turns out a girl did, but I didn't know it for a few years. That's another story) When I would get back to where he was I never knew if I would find him on his knees waiting to suck my cock, or standing there waiting for me to suck his. Either way was fine with me.

He was also the first guy to fuck me in the ass and the first to let me fuck him. (Also, another story.)

He was one of two regulars I played with in those days, I'll tell you about the other soon. In all there where 6 guys I played with between 1976 and 1981. The older I get the more I miss cock.