Idiot meatheads that have moved on from hanging out in the weight room listening to metallica to attending hardcore concerts with the intention of "fucking kids up." A vast majority of jockcore kids are insecure straightedge kids who take their teen angst out in the pit.
Jockcore Kid: Dude, tommorow, I'm going to the Throwdown concert and punching everyone smaller than me in the face.
Me: You're a fucking moron. /wrist please.
A music genre. It's the concept of making a song that seems like a joke and/or a waste of space and memory. Typically sent as a file through file-sharing sites to trick a user to believing they downloaded the right song.