Having been a sailor for 40 years, I am better at "red&green" than "left&right", and I always knew that red was on the left and green on the right (duh, obviously).

When I was young, my dad (also a sailor) even made a point of mounting one red and one green grip on my bicycle handlebar; of course I did the same with with boys' bikes.

Well, today I learned that this is called "Region A", and the Americas and a few other countries are called "Region B" where the red&green is reversed: red is on the right (and green on the left)!

To make things even weirder, navigational lights are not reversed in Region B.

Mind blown.