Don't let the audience pop your balloons.....

Do them youself, seductively, teasingly or if you do want a smidgen of audience participation - pick one person you know or looks trustworthy and get them to do something like this, on just one balloon at the end:
Lili La Scala's Balloon act
I know some people do let members of the audience pop balloons, but I just think it's too risky.....ask the lovely Angel la Vey what happened when her very loving husband got too active popping her balloons...and she trusts him....you don't know the audience, and they don't know their own strength