I have always, for as long as I can remember, associated numbers with colours. Two is yellow, three normally green, four blue, five always red, eight feels like brown, one is sometimes white. It's hard to describe how it works, but my brain pretty much interchanges the colour and number; for example when I was writing the previous sentence, I could just as easily have written 'yellow is two' or 'red is five'. It also works with some letters, like 's'. Red=five=s.
Now you're thinking I'm crazy, but it seems to be quite common. It's when your senses are intertwined, and some people see sound, feel words, smell colour, etc. It hasn't affected my life greatly, but I suppose what amazes me about it is that my brain has found a way to use my love of colour in an unexpected way. And now Craig has discovered a new word to tease me with :)