I yelled out "WTF!" in the office when I saw that a steep peak in the graph indicated a query that took 8MS. Turns out it meant to say 8ms.

The M means Mega (one million). We, I assume, are all very familiar with it, and therefore I assume that I'm not the only one who automatically reads it as one million.

Note that I did not confuse the s and S. That is because the s and the S are much less visually distinct. Still it's technically incorrect too.