The one I can't understand is that several years ago the scientific journals I publish in insisted that we no long use millibars as a unit of atmospheric pressure, but hectopascals (ie. 100 pascals), which are exactly the same thing. Now you find people who read "850 hPa" as "850 millibars", as if millibars just has a new abbreviation. Very odd that hecto-anything is considered a standard unit.

I can generally deal with both English and metric units, but I absolutely cannot abide the Rankin scale.