When I was a beginning student pilot I spotted a set of three coloured lights on the communications panel of the training plane and asked my instructor what they were.
He said, "Those are marker beacons, but they don't work: they're American."
Later I encountered a logbook notation that the landing light was "U/S." I asked what that meant.
"It means it's broken."
U/S, U.S., U.S.A., American, broken. Okay, they all mean the same thing. Aviation slang is strange sometimes, I could deal with it. It was a while before I discovered that marker beacons really are an American system, that U/S means "unserviceable," and that "American" isn't really pilot slang for broken.
I still giggle inside every time I see an airplane with US Airways stenciled on the fuselage. I believe the Americans prefer the term INOP for their broken equipment, so it isn't so funny for them.