Craft Stick Catapult - I made 4 of these in 5 minutes and they work great! You need craft sticks, 4 rubber bands, hot glue or tape, and a bottle cap (I cut apart an egg carton because I didn't have any bottle caps).
A water balloon with a glow stick on the inside, in a stocking, hung from trees, patio cover, or the ceiling. Same pin elsewhere said: "Put a glow ball in a white stocking and hang many from trees or the ceiling." But what are glow balls?