게 장난치다

mess around, play a prank

장난치다 is playful mischief — teasing someone, fooling around instead of being serious. The -게 adverb characterises the teasing: 약간 일부러 짓궂게 장난치고 "tease on purpose, mischievously," 진짜 귀엽게 장난쳤을 때, 엄마도 헷갈리게 되게 장난치는 거 많잖아요. Most lines use 이렇게 to point at what just happened (조금 이렇게 장난치는 건데). It is not a hostile word; the worry it raises is being told off (이렇게 장난쳤다가는 혼날 것 같고).

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