1. Good, but not good enough for one to raise whole thumb - thumbs up - a halfhearted sign of good job.
2. Most Likely used when while playing a sport and that one kid thinks hes really good, and everyone tells him hes really good but behind his back your laughing becuase he just fell flat on his face trying to catch a Frisbee. And he still missed.
Example; Wow. You were so drunk you fucked your own sister. Nubs up dude.