Let's take music as an example.
In high school, music isn't just a matter of personal preference, it defines what social team you're on. In my school, the rednecks listened to country, the tough guys listened to metal, the weird kids had the alternative stuff. What came out of people's car speakers was as important as the clothes they wore, or the slang they used. And each group was grading how "cool" an outsider was by whether they liked that same music.
"Have you guys heard the new Creed son- OH GOD, WHY DID YOU STAB ME?"
Then at some point in your 20s, you get to experience the bitchslap realization that the music you loved as a teenager was specifically designed to appeal to teenagers. And man, I'm telling you, it happens all at once. You'll flip around the radio or turn on one of the MTV channels that still plays music, and suddenly it hits you that what you're hearing is just absolute shit.