"Menacing", or ゴゴゴゴ (gogogogo), is a sound effect used in JoJo no Kimyou na Bouken, commonly used in the presence of dangerous or intimidating characters or objects. It is an example of gitaigo or "phenomime", a sound effect that represents a mood or feeling rather than an actual sound.
The tag name comes from the fact the official subtitles for the anime, provided by Crunchyroll, will often translate the text, as it appears on screen, as "Menacing".
