I'm straight, but I did have my cock deep-throated by a guy old enough to be my father, while hitch-hiking in 9th grade in 1970. Back then the most graphic porn I had any possible access to, was Playboy.
The driver had some glossy porno magazines strategically placed on the passenger seat, which I had to pick up in order to sit down. He suggested that If I like nude pictures to feel free to look at them. I said sure and happily obliged him! In conversation I mentioned I was coming from my girlfriend's parent's house. I was trying to appear casual as I flipped through the porn magazines. I became oblivious of the driver and had become intensely focused on the one gay magazine, which had HQ close up pictures of guys sucking cocks. It had never occurred to me to think about a guys cock in a sexual manner. I also had never experienced such intensely arousing pictures. I started squirming in my seat. He asked if my girlfriend sucks my cock. I said yes. Then he asked me if I liked having my cock sucked. Again I said yes. I was becoming suspicious of what he may be leading up to. But by then I was almost frantic to undo my tight jeans to adjust my raging hard-on. He then asked if he could suck my cock. I blurted out 'YES"! I immediately started undoing my pants to let my cock out. What a relief! Before I knew it, he had pulled over and was throating my cock! At first I was nervous that I was getting my cock sucked by this stranger, but then I realized that this was an enjoyable experience and that this opportunity may never come again. Once I relaxed I could feel my cock hitting the back of his throat and then shooting a huge load of cum down his throat. It was the best blow job I ever had. I still jerk-off thinking about it 50 years later!