Those kids who hate everything that is popular and make themselves like things that everyone else hates in the hope that it will make them stand out and be "original" or "unique." The kind of person who instead of jumping off a cliff if someone else did, would jump off a cliff if everyone else said it was a terrible idea.
Not to be confused to with nonconformists, who choose their own tastes uninfluenced by others.
Joe: "Hey Mary, have you heard the new Katy Perry song on the radio yet?"
Kara: Oh my GOD that song sucks! Who honestly listens to that crap?"
Joe: I know, I hate it.
*Kara walks away*
Mary: She's never even heard the song before. She just hates it because it's popular.
Joe: Wow, what an anti-conformist.