well, it's not really painting. But, if you take a white pumpkin, tape a few different colored crayons, and use a hairdryer to melt them, then the wax will drip down the pumpkin, and it looks really cool.
Humpty Dumpty - Paint top half of an oval-shaped pumpkin with white paint. Paint on facial features (look for cute pics of humpty online) Either paint on clothes or use felt to make clothing. Add a small black hat (from craft store) Draw/paint a brick wall on posterboard and tape to front edge of table. Place Humpty near edge of table in front of the "brick wall" poster. Will look like he's sitting on top of the wall.....make sure he doesn't fall!
Well, what i did with my little brother was a frankinstien jackolantern and he did a vampire and got all crazy with the red paint, you know what i mean by that. But yeah, he had a blast with it. I recomend you dont use washable paint. Made that mistake already. Stupid idea.