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Niner Syndrome is when freshmen come to high school and think they're the shit, just because they were the seniors back in middle school last year. Niner Syndrome can result to an unnecessary boost in ego, thinking you're the shit, talking to everyone like you're bigger than them, thinking you're the most important person around, etc.
Alex: Dude, what's with all of the Niners this year?
Dave: They have Niner Syndrome.. but a nice initiation should be the best medicine!
by Diabba September 02, 2011