The silliest non-music related complaint came from a parent of one of my kindergarteners, a few years back. She called the director of the school to complain that I had taught her daughter to make an "8" using this rhyme: "Make an S, and do not wait; come back up and make an 8."
She was angry because she wanted her daughter to make an "8" with 2 circles...

The goofiest music-related complaint came from a woman at a historical farm, where another woman and I were playing out in the gazebo. As I frantically searched to find a power source for my digital piano, (they said there were outlets in the gazebo--and there were; they just didn't work!) she followed me around, saying, "Where's the GUY? I thought you had a GUY! Isn't there a GUY?--" on and on, until I thought I'd have to strangle her with the 500 foot extension cord I was running out from the farmhouse!