I reserved the Explicit tag for Comics that I think go too far.

Either the use of violence, gore or sexual content is extreme enough to shatter your suspension of disbelief in the Comic being real, there is no justification in the story for the violence/gore/sex that we see, the violence/gore/sex seems to be the only reason for the series' existence, or I just feel it crossed too far over some kind of boundary.

You might want to avoid reading an Explicit Comic in public, depending on how embarrassing the comic is and how misanthropic you are.

Occasionally a formerly reserved series suddenly includes a scene featuring strong language, violence, gore or nudity. In these cases If I see a series doing that I'll give it the higher age-rating, while explaining that readers may not see evidence of this until later in the series. Be aware that my initial impression reviews, which only cover the start of a series, may not catch these cases.