In journalism, Green Ink is (humorously) supposedly a major identifying characteristic of written correspondence from self-aggrandising pedants, cranks, charlatans and eccentrics.
Although no psychiatric equivalence with the preceding terms should be inferred, it is also used to refer to unusable correspondence originating with readers who are mentally ill.
Regardless of the colour of ink used, it is common to refer to correspondence of any kind (including email and webpages) as being in "green ink", so long as it broadly fits the following identifying characteristics:
Stridency
Impertinence
Unreasonableness
Unrealism
Fancifulness
Obsessiveness
難しい単語が幾つかありますが、要は "green ink" は青インクの意味ではなく書かれた内容の問題であり、青インクを "green ink" とするのはベトナム語特有の表現ではないかと推測します。
今日のハーフマラソンは自己最低記録でした。やはり練習不足では駄目ですね。