This tutorial can be found in full with step by step photos over at Art Mind. It's a simple process of covering your surprise design/verbage with clear sticker paper and then mixing paint and dish soap together, to be applied over the top.
Not only is this a great idea for party favors, invitations, or party games in general, we also think it would be a fabulous way to keep daily chores entertaining! This is one of those projects where it's just as easy to make 100 as it is 10, so make up a bunch with different chores hidden below. Draw them out of a hat and allow kids to scratch off to see which chore they've drawn.
Thanks Art Mind, we'll be putting this one to use soon!