Joking aside, one of the worst things about America is the mixed usage of metric and imperial. It sucks having to convert everything all the time, particularly when you're working on something that uses both systems for one task and you have to make them play nice together.
The other worst thing about America is all the mass killings.
And the same Americans who rage against the idea of converting to metric are the same ones that name their 9mm pistol Sheila and drift off every night petting and cuddling it.
I’ve been to Puerto Rico recently, and noticed a weird metric / US customary mix
For example, when driving on the highways you’d see the distance markings in km, but the cars often had mph on their speedometer, with km/h as small markings on the side