Is this normal for a 3 year old?

My son (3) for the past month will only let me refer to him as dash from the incredibles. And he calls me elasta girl. It was cute at first but I’m growing more concerned as it doesn’t seem to come to an end. If I call him by his name or ask him to do something he won’t do it and says “no I’m dash”. I was just wondering if this was normal/common? via /r/Parenting http://bit.ly/2Lin2Dk