I coach girls soccer, they were 12 years old last fall. One team last year had a parent that had a horn - perhaps one of these things. It was annoying and obnoxious. They would blow it not only in excitement, but also when one of our girls was with the ball near them. A big distraction to some of the less confident girls.
I suppose if it gets out of hand I can mention something to the ref about it. Parents can not “missbehave” on the sidelines. Hard to prove though that blowing a horn to distract a young player is missbehaving. Swearing at a player or yelling “knock her down” is much more obvious.
The vuvuzela is perfectly shaped to be inserted into one or more of the vuvuzelist’s bodily orifices ...