The basic premise is that someone posts a picture and then that picture is altered, and then that new picture is altered and so on. It often results in some amusing end pictures.
Hmm.. Examples, examples.. Here's one, copied from MSN using MSN handwriting to make the pictures.
Tools? MS Paint or programs of like kind, preferably.. Beautifully crafted pictures may well look great, but they're hard to alter effectively. Same goes with animated GIFs. Since you can't directly post images here, you'll need somewhere to store them on the intarweb. And retrieving a picture is easy, right-click and "Save As" or similar in most browsers.
Rules? None, other than nothing offensive. You can alter the size, colour, whatever, and it's almost (but not actually) required that you add something new to it.
I'll start off then, with.. A circle! Well, it can pretend, anyway.



























