I thought that at first - but what if you want a digital copy; what's the plainest, whitest thing you can find to draw on, and do you have a scanner?

Obviously a lot of the time if you're going to the deliberate trouble of creating a digital image, you'd probably prefer it didn't look hand drawn... but I can imagine seeing it in repo readmes; that sort of thing. Actually that's quite appealing - because you could source control the ASCII too.