I took high school and college physics courses (in the US) and have spent 15+ years developing physics-related software and I don't recall ever hearing gravity expressed in ft/sec^2. I can't gauge whether this "familiar" principle is itself a joke or if there are places where gravity is taught as 32 ft/sec^2 rather than 9.8 m/sec^2...
These days I'd think it almost unconscionable to teach kids scientific measurements in anything but metric.
Maybe we'll get metric units in Physics.
I prefer miles, feet, and farenheight for every day use, but for science metric is king.
It's all labeled in ft/sec^2
It's expressed as convenient to the problem.
For example, muzzle velocity is always given in ft/s in the US. So for ballistics problems (faster than a speeding bullet...), ft/sec^2 would probably be used.