Copyright: vore day
August 8 is Vore Day, a day to celebrate vore.
The "holiday" is a meme within the vorarephile community, and is generally a day for content creators to share new vore projects with the community or showcase previous vore-related work. Some artists may create content that specifically references the vore community and/or the day, while other artists may do drawing streams or take requests from fans to mark the day.
In terms of tagging, Vore Day may be referenced in text, dialogue, or by having the date — 8/8, written somewhere in the scene, or written on a character's belly. If the image/animation was merely created for vore day, or released on the 8th of August, and has no obvious references to Vore Day, the post should not be tagged as vore_day.
Why 8/8?
The exact origins of the meme are unclear, but the use of 8/8 as Vore Day began among Japanese vorarephiles on Pixiv sometime around 2012, and later spread internationally in English-speaking spaces. The first known instance of this event was organized by an artist named イスタッシュ on pixiv. 8/8 was chosen as the date because it is a play on the word for vore in Japanese, 丸呑み (marunomi) which is pronounced the same as 丸のみ which means "only circles" and 8/8 is a date that can be written with only circles. Coincidentally, in English, 8/8 can also be a vore related play on words as the date can be read as "Ate-Ate".
There is a mistranslation/misconception that the date is an onomatopoeia in Japanese. Specifically that 8/8 — ハチハチ (hachi hachi) — is an onomatopoeia for a growling stomach which is not true.