Years ago, at Borders Books & Music, I told a clerk that a book I was buying was "a strong primer on music." I pronounced primer with a long i.
"Primer," the clerk said. "That's one of those unusual words. It's interesting how it's pronounced with a long i in the context of painting but with a short i when it refers to a book."
After I paid for my purchases and drove off, I thought, "That was the right way to correct someone--explaining the difference between the word's two pronunciations politely. That's much better than saying, 'Arrrrrgggghhhh! Primer is pronounced with a short i in this case! Geez! Doesn't anyone know anything anymore?!"
