A Catcher for Christmas

This morning my son, who is 5, didn't want to go to school. He told me that it was because this girl, Maggie was bothering him. She didn't let boys play with her and made the rule, "No boys allowed." So, I asked my son what would make it OK for him to go to school today and he said, "If I had a catcher." I could not figure out what in the world he meant by a catcher. I asked him, "What kind of catcher," and he said, "A Maggie catcher."