- When you don't know anything about linguistics: The plural of "memorandum" is "memoranda", why can't people get it right
- When you know a little about linguistics: The plural of "memorandum" should just be "memorandums" because that's how people naturally say it, "memoranda" is just prescriptivism
- When you know a lot about linguistics: Oh my god? So certain English words borrowed from Latin and Greek have competing plural forms, with one form using the English plural -s and the other using a borrowed Latin or Greek form? Do you realize how crazy that is - a language borrowing *inflectional morphology* from another language? And here the two competing plural forms have become markers of education, expertise, and social class, isn't that incredible?
ACTUALLY the plural of "Platypus" would just be "Platypuses," as the "i" in words such as cactus/cacti is exclusive to words with latin roots, whereas the "pus" in "platypus" is of greek roots, meaning flat foot in greek. So technically the plural should be platypodes, as that is the greek plural for feet, but it has fallen out of disuse in recent times, leaving us with the much more simple Platypuses. The same goes for Octopi/Octopuses.