The phrase references a specific character from the Dragon Ball franchise paired with sexually explicit content. It denotes fan-created material, often visual in nature, that depicts the character Android 21 in a pornographic or otherwise sexually suggestive manner. This kind of content is usually found online on various websites and platforms that host adult material.
The popularity of this specific subject matter is linked to several factors, including the character’s design, her perceived attractiveness, and the general appeal of the Dragon Ball series. The widespread availability of internet access and image-sharing platforms facilitates the creation and distribution of such material. The demand for this stems from the existing fanbase’s interest in the character and the overall prevalence of Rule 34, which postulates that if something exists, pornography of it exists.