DS1 is 5 today. He had a small party for a few friends and PIL. One of his little friends was looking at DS2 (5months) and said to Ds1 'Is it a baby brother or a baby sister'. DS replied, quite seriously ' Mummy says he is a baby mutant'. His friend nodded as if that was a reasonable reply.
I have no idea what he meant. I am sure he has no idea what the word means. I certainly did not say that and would never say it.
DH has been calling DS2 Donatello for the rest of the day- much to DS1's bafflement!