With so many people now in the world, hardons must be more common than we might imagine?
I wear boxers, and most of the time it works fine. If I get a semi, no problem; it just elongates on the right side of my leg. If I get a full boner, it lifts up and it's very obvious.
But a semi feels very good, so is it hard to keep it from quickly "boning up?"
I used to get "logs" down my pants leg, in class, during puberty, until I started getting some control with age.
Generally in school, nobody would much say anything or seem to care, but I think a few people must have noticed, for I found a condom on my desk one day, and some guy asked me some day later or something, how long it gets when hard. I was embarrassed to answer, so he pointed on a ruler, and when he got to 7 inches, I said yeah, only he was to 8 inches by then, and he seemed to believe it. Yeah, must be hard to do those "mental" calculations of bulge size.
I saw some other guy with a bulge thrusting up under his zipper, but either nobody else noticed, or more likely, they wouldn't let on that they noticed. That's what happens when you are trapped in class all day, going through puberty. Sometimes that penis just can't relax and get a bit excited. I think often people don't say anything, because it happens to them too, and they don't want anybody making a big deal either. And were they to say anything, the "show" might go away so they can't sneak a peek anymore?
And then, it's not always so obvious as people imagine, as people do tend to "mind their own business," and they don't feel it, like the person would having the erection.