The significance of the colors in the diagram on the whiteboard might not be what you think they are when the person doing the drawing is red-green colorblind.
There's a usability lesson here, or at least a reminder of one.
It's irritating to others that I always ask for something else if I'm given a color as an identifier. "The red one!" "You're going to have to tell me something else about it." If I had that on a tape, it would remove perhaps 3% of all the speaking I do in a year.
Usually, given choices, I pick red or green and some other colors, blue and yellow if possible. If someone says 'red', I know they mean the one that's red or green, and same for if they say 'green'.
Of course, none of that's really a solution.
