"What are "bong hits"?"
A bong is a water-pipe-like device pople use to smoke pot. Often the bowl is just big enough for one pinch -- also called a hit.
See, I learned something in college all those years ago.
"Often the bowl is just big enough for one pinch -- also called a hit."
That's a "One-Hitter." C'mon, get up to speed on drug phrases, will ya?