What Would Happen If Peter Pan Did Grow Up? Peter Pan was supposedly a boy who never grew up. Though chances are good you probably grew up watching the iconic movie. Now as a grown man, nothing is stopping you from reveling in the nostalgic joy of this beloved movie. Especially, when there’s this adult Extra-Large Peter Pan costume just waiting to be worn! A Peter Pan Costume To Help Keep You Warm On Halloween Night This Peter Pan costume is available in extra-large and is voluminous. This makes it easy for you to dress warmly underneath, without having to cover up the detailed costume with a heavy coat. It’s perfect for tagging along with your kids trick or treating on Halloween night, dressed as your favorite childhood character.