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Comic strip of a ghost and a person with the American flag pasted on the head. The ghost repeats “Boo!” in the first three panels without getting any reaction, but when it in the fourth panel says “kg, cm, km, °C” the American gets scared and screams “AHHHH!!!”.
Edit: fixed alt text
I use both equally well. Since both of them are base 10, no difference whatsoever. You just know the feeling of 70F or 21C.