This was on FB, so I couldn't really link to the source, but it said (in Spanish): How to fill balloons at home - Replacing the Helium Gas No more run behind helium to fill balloons ! You just need to mix vinegar and baking soda!
Celebrate the grad! Make clear balloons more festive (and less boring) with confetti! Sprinkle small amounts of tissue-paper confetti through the mouth of the thing, then blow it up and shake to dispense it around.