For a royal party! (Or a medieval fest!)...The girls could wear these, and the boys could wear a king's crown or knight's (faux) headgear... Make them plain and then decorate at the party! ...But do this before age 5 or 6 - children any older than that will probably no longer be interested in this theme!
BEST website for Themed Parties ever!!!! It seriously has every theme!
Another pinner: Ranblow Spatter Cupcakes. "I've made these so many times, I've lost count. Using white cake mix, make batter as directed. Use several plastic (or glass) cups, pouring white batter in them, divide between all cups. Add food coloring to each cup for the colors desired. Mix each cup and then put a little of each color in each muffin cup in small blobs. Then drizzle other colors over the blobs. Bake as directed. My kids always wanted these for every birthday and special occasion."