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overly familiar; overfamiliar; too friendly; too free; cheeky
初対面なのに馴れ馴れしい態度だった。
Despite meeting for the first time, they were overly familiar.
初対面なのに彼の態度は馴れ馴れしかった。
Despite it being their first meeting, his attitude was overly familiar.
彼女は親しいが馴れ馴れしくない。
She is friendly but not overly familiar.