Take an empty coke bottle and fit it into a balloon. For adding a bit pop to this idea you could also decorate your balloon with beads, studs or design them with markers and glitters- after fitting the coke bottle.
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?