1) To open and unpackage something, generally for the first time.
2) To operate a motor vehicle in a spirited fashion.
3) To commence, or return, fire at a person or thing.
1) Hey, let's go open up that new PS3.
2) Yeah, just a few minutes ago, we had 'em opened up out there on Redwood.
3) Why don't we take the 1911 out and open up on some bottles and cans?