1) Get it done, as in win the game, etc
2) Let's do this, entailing excitment or anticipation
3) Do it BIG. As in a party being lavish or extravigant.

The "st" on the end is integral.
Person one: "Dude im gonna get hella chips and drinks for the game this saturday"

Person two: "Awww yeah! Do it UPST!"
by Michael Wayne January 13, 2007
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