A. To, through no skill of your own, make something fortuitous happen. or
B. To seriously screw up something. or
C. To burp the worm (masturbate).
A. You bastard! How did you jag that? (after winning a prize)
A. Somehow jagged that one! (after fluking a pool shot)
B. Oh fuck! I jagged it! (after missing a pool shot)
C. I didn't have anything to do, so I jagged it 'til it bled.