Ad Hominem

I was at a baby shower today, and my two cousins were talking about the types of icing on the cupcakes. One of them was sure that the icing was some sort of chocolate, the other knew that it was chocolate pudding. When they were argueing back and forth, the one who knew for a fact it was the pudding, had for sure declared that it wasnt icing at all, the other cousin had said, "well you know what else isn't icing, YOU RACE." I right away grabbed my phone and wrote down what he had said because i knew it was an Ad Hominem.