ineffective censorship
When a censor isn't censoring the thing that was intended to be censored. This is usually because of an extremely thin and poorly placed censor bar (whether on purpose or not), but it can also be because the artist simply wanted to be funny.
This is often done by Japanese artists as a token to comply with the vaguely-worded Article 175 of the Japanese Penal Code which prohibits distributing obscene imagery.
A more effective version of this would be fill-in_censorship.
See also
The following tags are aliased to this tag: ineffective_censoring, pointless_censoring, uneeded_censor, useless_censorship (learn more).
This tag implicates censored (learn more).