As a Canadian, I can give a pretty good go at this as Crichton does a beautiful job of showing a mixed system at work. Canadians should be Metric, but we exist in a weird middle space. Ask a European traveler here, we are weird for this.
I am 6'6"...it's almost 2m exactly, but if I told a fellow Canadian 2 meters, they'd be confused until I said feet inches. Same with weight, we talk our bodies weight in pounds despite it being clearly written in KG on my driver license. My fruits and veggies are in grams and KG. Oddly, I know my car's weight in KG...if you asked me to tell you my combined weight when I'm in the car, I'd have to go through math in my head to convert my cars kilo's into my bodies pounds or vice versa.
Distances are meters and KM. I drive in KM. I buy litres of fuel. Ask me to tell you my cars fuel efficiency and I'll answer in Miles per galleon without blinking (and will readily say I bought 10 litres of fuel and go 33 mpg in the same sentence).
I can go through many of these (some of them to the point of complete absurdity to be honest), but to generalize...anything that is exacting or that I need to pay for is in Metric. Anything that is relative or conversational tends to be in Imperial. Crichton does an amazing representation with the quote in the accepted answer:
"Pacific coral grows two-and-a-half centimeters a year, and the object-- whatever it is-- is covered in about five meters of coral. That's a lot of coral. Of course, coral doesn't grow at a depth of a thousand feet, which means that the present shelf collapsed to a lower depth at some point in the past."
I have actually said the following line and been completely understood myself... "We've been driving for hundreds miles, but down to 22km to our turn off".
Temperatures are even weirder...I don't know how hot 65 degrees Fahrenheit is and translate it to Celsius, however if you asked me what temp to start the oven at to bake a pie, I'll list Fahrenheit without question. When I tried baking at 220 Fahrenheit and messed up cause that number was supposed to be 220 Celsius, me and my friends all echo'd the same sentiment...what nut jobs cook in Celsius?, err but it's cold in here, turn the thermostat up to 21 fo me.
I give Crichton full marks in accurately portraying the use of a mix measuring system very accurately.