I think I still have at least one "This shirt is a munition" T-shirt with machine readable (barcode) RSA code (in C?) on it. That might be what you're thinking

I think I still have at least one "This shirt is a munition" T-shirt with machine readable (barcode) RSA code (in C?) on it. That might be what you're thinking of. The point wasn't to circumvent anything but to draw attention to the absurdity of the rules, which persisted for quite some time after the shirt. The equations themselves were never export restricted, nor was computer code printed in text in a book (since OCR wasn't considered good enough at the time yet). It doesn't stand out as a great example of "on the other hand".