Four years ago. My daughter 2.5 and son 4.5yo. Morning, me and the kids are playing birthday party. We are having lots of singing and blowing fake candles on a fake birthday cake. At the end I pretend cutting the cake and putting on my kids plates imaginary pieces. My son (always jealous that his sister has everything better that him) is saying to my daughter: "oh, you have got a bigger piece, let's swap the plates"