说人口是心非的才口是心非
[shuō rén kŏu shì xīn fēi de cái kŏu shì xīn fēi]
'Those who say someone is insincere often speak insincerely themselves.' A defensive nickname that may stem from having been wrongly judged. The individual might believe that those quick to point out hypocrisy may have their own secrets or deceptions, serving as self-justification or an indirect challenge towards critics.