"dear industrial nincompoop: please explain why your design is suboptimal"
"dear professor nincompoop: your model is wrong and we need calculus that you don't teach undergrads"
"In calc when teaching the 'min surface area of a can with given vol, of which soln is diameter = ht, I wrote a cat food company telling them how much they'd save by making their cans taller. Got a letter from the marketing dept telling me a million reasons for the cans' design." - original tweet