Rule 63 is a well-known internet adage stating that for every fictional character, there exists an opposite-gender counterpart. Originating from the 'Rules of the Internet' compiled on 4chan in the mid-2000s, it focuses on the creative reimagining of male characters as female and vice versa. While primarily a guideline for fan art and cosplay, Rule 63 became a widespread meme used to showcase high-effort character redesigns or to poke fun at the inevitability of gender-bending in online fandoms. Today, it remains a cornerstone of internet culture, fueling endless creativity and discussion across social media platforms and art communities.