Nappa is a character from the Dragon Ball franchise, which is a popular anime and manga series containing elements of fantasy and science fiction. The term "Nappa" as a porn video tag typically refers to content involving the character Nappa or similar-looking characters with similar appearance features (e.g., spiky hair, facial markings). This tag may be used by fans of Dragon Ball who are also interested in adult content featuring their favorite characters. However, please note that this term is not directly related to explicit sexual content but instead refers to a specific character or style within the context of porn videos.