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1.
A drinking game involving drinking a beer every 30 minutes for 12 hours. You must finish each beer before the beginning of the next 30 minute increment or else a penalty beer is awarded. Invented at the University of Texas circa 2007.
We tried to complete a power day, but 24 beers was too many.
by cstevens2010 July 30, 2011
 
2.
taking one shot of hard liqour, every hour, for 24 hours straight without sleeping. (drinking in between is encouraged but optional)
"Yo Captain, fuck power hours, lets do a power day and get fucked up"
"I'm game"
by Captain Karl March 12, 2008