Brilliant: "Y Combinator is about 3 months long (June through August). 18 hours a day * 3 months = 1620 hours. Incidentally, that means my weight increased about 4.5 grams per non-sleep hour of YC. This is roughly equivalent to 1 paul gram."
I spent a while trying to figure out how 4.5 sleep-hours^-1 was equivalent to 1 paul, and why this is funny, until realizing that wasn't the intended joke.