My boys love to get messy. I found this wonderful idea on the Imagination Tree website. I simply cooked up some spaghetti (doesn't mater if it's undercooked a bit). After draining it I added a bit of oil and food colouring. Only a few drops worked well. We had a great time playing although cleaning up the yard wasn't so fun for mommy but it was worth it.
We even added some toys to the mix
Check out the Imagination Tree for more fun ideas for kids. My blog also has more activities listed under games and cfats