We have the gadget that will cheer everyone up, young or grownups alike: Glowing LED balloons!
Just pull out the security strip and blow up the balloon - and you have a colourful LED flashing balloon!
Tip: You can use the LED module again. Remove it after the party from the (burst) balloon and plug the security strip back into the battery case. Then you can use it again in a new balloon any time! The LED modules can of course be used with all standard air balloons, also with printed balloons for example. Pay attention that the balloon's material lets enough light through, thus not being too dark.