>If you want to amuse yourself, count the times you see people write things like "$10 dollars". It's quite common. Technically it should mean 10 square dollars, whatever that is.

Not quite the same thing, but I had a senile biology teacher who looked for any pretense to deduct points on papers. For example, when you reported data from lab work in tabular form: "points off -- these numbers don't have units". "But the column headings indicate the units -- that would make it redundant!" "Not good enough."