带着红领巾耍流氓
[dài zhe hóng lĭng jīn shuă liú máng]
This uses the contrast between innocence (symbolized by the red scarf, typically worn by Young Pioneers in China as a sign of purity and honor) and misconduct or bad behavior (suggested by the colloquial term for behaving improperly). It humorously depicts hypocrisy or misbehaving despite appearing outwardly respectable.