Regardless what the FAR/AIM says, small unannounced party balloons don't gently float by when you're well in excess of 100MPH. The brain (already taxed with other tasks at hand) has very little time to comprehend what it sees before taking an evasive maneuver. It can and has been a very jarring experience.
Most people I think would recognize the potential danger of tossing such a seemingly harmless object in front of a race car and yet there's very little difference for a pilot.
I'm asking for your compassion and understanding as a fellow human.
If men are good, you don't need government; if men are evil or ambivalent, you don't dare have one.