client: "I'm happy to see you've made most of the changes I asked for, but why is there still green on the page?"
me (looking at the now entirely red, white and blue page, not an earlier green prototype): "There isn't any green on the page... where do you see green?"
client: "The buttons are still green"
me (looking at blue buttons): "The buttons look blue on my screen"
client: "oh, well it must be because i'm colorblind"