Packing your backpack just before the end of class as the teacher is giving the last information like homework or reminders that "There's a quiz tomorrow!". Useful before lunchtime to gain a jumpstart in the lunch line or at the end of school.
Joey: What the hell? How did he get the the front of the line?

Mac: Preemptive packup i bet.
by TheNarcwhal March 17, 2011
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