Kids are mean, as we no doubt all experienced when we were younger. They prey on weakness and difference, and they’ll change best friends on a whim, or because someone used the pencil they wanted.
In this case, the storyteller has obviously never let this one go, as he remembers vividly how he was uninvited from a girl’s party. Not just this, but he had to tell her how to spell his name so she could put him on the persona non grata list. How embarrassing.