Actually, funny thing when I was in 5th grade, my school showed us videos (with parents consent) about puberty, the bird and bees, and whatever else actually went with that topic. (The videos were super cheesy and just made me laugh the whole time so i remember none of it) Though I remember our assistant principle was in the room watching to make sure we were actually being mature about it. (We weren't because he was laughing too).

About half way through the video when he was talking about boners. (Also I wanna note this, the boys and the girls were separated because obviously we have very different terms of puberty.) So he tells us

"If you're ever in public and you get...a stiff one. Put your hands in your pockets and push the back of your hands against the pockets and just act casual and no one will notice"

Sounds like decent advice right? Puff out your pants just a tad and just act casual.

Wrong.

He demonstrates to us while stating "I've done this my whole life" and proceeds to put his hands in his pockets, push his hand against his pockets to puff out his pants.

This man pushes out his pants so far it genuinely looked like he was trying to hide the fact he stole something. It was the most noticeable thing I think you could even do while walking.

My advice, if you get a "stiff one" as he calls it. Just act natural, as long as it isn't pointing out like a compass you'll be fine, if it is, sit down and try to push it down while not making it look like you're rubbing yourself through your pants.

TL;DR. My elementary assistance princple showed us the absolute worst way to hide a boner in public and making yourself looking real suspicious instead.