We often play board games, card games or have pool races at our house and are trying to teach my daughter to manage her disappointment when she loses and honestly she has been doing pretty well with it.  But Saturday we were in the pool and she and her dad were racing and I was the judge calling out the winners (in hindsight I probably shouldn't have been doing that).  In one of the races, dad won and she had a total meltdown saying "daddy cheated, I hate Daddy, etc. etc. etc."