I teach English in a Spanish school. This happened with a class of 7-8 year olds. There was a boy who was a really nasty piece of work, Not mean or naughty, just a disgusting little bastard. Ate all of his books and pencils, literally, and always had a smell about him. I had talked to his dad on an occasion but he refused to believe it (all parents think their kids are angels). He had a habit of drawing sick things, like a faeces based restaurant. Poo lasagne, poo pizza, piss wine etc. I always took these drawings off him. One typical day he was drawing something so, as always, I went up to him to take the drawing, the bastard started running so I chased him, much to the amusement of his classmates. I finally catch up to him and I observe the piece of paper, it had drawn on it two stick figures, male (short hair) and female (long hair). The male had what looked like a thong and and a bra on and the female boxer shorts. I asked the boy what this drawing was and his answer:
"It's mummy dressed as daddy and daddy dressed as mummy".
Two days later I showed the drawing to his father, along with his sons description. I will never forget the look on his face.
I still wonder if it was just the boys imagination or something he had seen.