Another threatened legal action against a school after she heard that sodium chloride had been spilled on her son's arm during a science lesson.
Even after teachers explained that this was the chemical name for salt she was reluctant to back down.
The incidents are just some of the parental complaints reported by readers on The TES website.
Another mother complained after her son ate a satsuma during break. She told teachers her child was not allowed orange squash or fizzy drinks because of his hyperactivity.
But even stranger complaints were sparked by misunderstandings by children.
When a parent asked her son what he had been studying, he replied that they had done "b****r all this term".
The parent challenged the teacher, who explained the class had been studying Buddha, pointing to the wall display on Buddhism to prove it.
Some parents accused staff of traumatising their children by calling them such innocuous names as "nibbler", "turnip" and "sleepy head".
Others thought that teachers were not tough enough, one mother saying the school should not have given her son detention but "shouted at him and smacked him one" instead.
Dick Boland, south-east regional secretary for the National Union of Teachers, said the stories he heard from teachers suggested that frivolous or misguided complaints by parents were rising.
"It's important to stress that the vast majority of parents work well with schools," he said. "But, as is so often the case, it is the minority who take up so much of teachers' time."