Lyric discussion by Azusanga 

Oh goodness.. It's about how people would bully Robert until he hit his breaking point, went and got a gun, and started a school shooting. People are focusing on "kicks" in the wrong sense... maybe it's not universal, but where I'm from, Kicks is another word for shoes, and shoes are very often used as a status symbol.. ratty shoes often mean you're poor, whereas the newest Osiris brand shoes often mean you have a high social status. "All the other kids and their pumped up kicks better run better run, outrun my gun" means that they better use their super awesome status-symbol shoes that are completely impractical to run, or they're going to get shot.

And it was probably the kids with the nice "pumped up kicks" that were bullying him because maybe he was kinda poor and the kids with the pumped up kicks (the rich kids or the popular kids) would tease him because of that. I think your answer is correct.

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