During the high-school years, boys are practically obsessed about sex. Even while still in primary school, my boy classmates were showing off hardons to each other (and sometimes to the girls, but mostly to each other). Several would even take it right out in class and jerk off.
By high school time, though, much of the sexuality I observed directly was in the locker room and in cars speeding around at night. School gossip regularly reported who had the biggest dick, and in the showers there was always a lot of (fairly covert) checking each other out going on.
In college, it was less covert, and at least among the crew-team boys with whom I often showered, there wasn't the slightest modesty about getting erections in the shower: everybody looked and many commented ("Whoa, baby, look at that wanger, will ya?").
A couple boys in high school really liked showing off their dicks. One or two have stayed in my mind as highly desirable. I've always thought it would be nice to run into Mr. A. or Mr. B.some day. There was no intimation then they would have been available, however.
Others definitely were available, even though it invariably required some sort of seduction scene. After you did it the first time, it was usually fairly easy to arrange to do it again. One friend and I did it in his car the first time, but then he wanted to go camping all the time. These trips turned into regular sex marathons. Of course, all this was considered highly irregular, and total secrecy was assumed, for keeping such activities in the closet was a given.
The last couple years of high school I had a six-day-a-week job as a copyboy at the newspaper. There was another guy there who was gay, and after work we would sometimes go in his car for a drive to some hideaway country lane and do things. I thought he had a very strange personality, though, very negative about everything in a kind of fake-dramatic way, so the friendship, including the sex aspect, was not really to my taste.