I guess for you younger cats it seem weird and gross but before the internet, there was a game called show me your and I'll show you mine you played with the girl in the neighborhood.....Children have no inhibitions about these things but eventually the girls learn decorum...I guess from that maturing early thing.
Boys, seeing as how the girls we used to innocently play with or beat up suddenly make it stiff we assume...."Ha, check this shit out now" and and this is where you find out where you stand on the penis hierarchy....Forever shunned or rumored about.....Usually this is created in middle school.
By high school, we have come up with no new ideas so we just modify the one we had.....Instead of showing it to you, we would wear basket ball shorts and sweat pants....The cowboy kids just wore reeeeeeeeeeaaaaally tight jeans. NOW it's like I'm not showing it to you....If you see it, it's because you're looking.....And that's how teenage pregnancy happens in the South.........
Wait, what was the question?