What is "third-grader"

Usage examples of "third-grader".

I'm getting more and more miserable and fed up with myself for smoking so much, this is after a couple weeks of it, is all, and I start getting high and thinking about nothing except how I have to quit smoking all this Bob so I can get back to work and start saying I'm here when people call, so I can start living some kind of damn life instead of just sitting around in pajamas pretending I'm sick like a third-grader and smoking and watching TP again, and so after I've smoked the last of whatever I've got I always say No More, This Is It, and I throw out my papers and my one-hitter, I've probably thrown about fifty one-hitters in dumpsters, including some nice wood and brass ones, including a couple from Brazil, the land-barge guys must go through our sector's dumpster once a day looking to get another good one-hitter.

I felt a shame and personal despicability no third-grader should have to feel.