Drugs have taught an entire generation of American kids the metric system.

O’Rourke’s line is a sardonic jab at two distinctly American realities: the country’s long resistance to adopting the metric system in everyday life, and the pervasive presence of illicit drug culture. The joke hinges on the idea that, while schools and civic institutions struggled to make metric units feel “natural,” drug buying and selling made grams and kilos practically useful and therefore memorable. Beneath the humor is a critique of misplaced cultural priorities—suggesting that practical incentives (even destructive ones) can succeed where formal education and policy campaigns fail. It also exemplifies O’Rourke’s broader style: using a punchline to expose social contradictions.