Standing in a frozen yogurt shop a while back, two friends and I pondered the nutritional details posted on the wall opposite the counter. The most health conscious of the three of us turned to me and the following conversation ensued:
Health nut: "How much is 42 grams of fat?"
Me: (after 20 seconds of thought) "1.5 ounces"
Health nut: (shocked) "How the hell did you know that?"
Me: (smugly) "Marijuana"
Health nut: (confused) "How did weed help you?"
Me: "Every stoner knows, there are 28 grams in an ounce"
Friend #2: (smugly) "Yup"

At this point the conversation stemmed to other things we had learned from interacting with drugs. Like the intracacies of Supply and Demand, and so on.

Later that evening, after dinner with my stepmother, the conversation came up again. She reminded me that there was only one reason that she knew that there were 2.2 pounds in a kilogram. Which, of course, when she was buying weed, was only $100. We noted that a similar amount would probably be upwards of $2,000 nowadays (especially since it was kind bud). A lesson in inflation too.

Don't say drugs never taught you anything.