Gas balloons, just baking soda in the balloons and vinegar in the bottle, when the balloon is flipped it blows up the balloon.
Here's a great experiment for collecting gas (and showing one of the signs of a chemical reaction).
Gas balloon - The first launch of a gas balloon by Jacques Charles and Les Frères Robert, 27 August 1783, at the Champ de Mars, Paris. Illustration from the late 19th century.
Wedding Balloons - my favourite wedding decoration detail
Albuequerque International Balloon Festival, Albuequerque, Oct 3-11
Gas Balloon Inflation
Not just for toddlers. Great party themes for birthdays or just for fun.
Relentlessly Fun, Deceptively Educational: The Balloon that Inflates Itself (a Science Experiment)
No helium needed to fill balloons for parties.....just vinegar and baking soda! i need to remember this! @patricia rosario