Why Did This Cute Dog Buy a Mermaid Costume? His Secret Plan is Revealed! 🧜‍♀️🐶

The provided transcript "진짜" (Jinjja), which is Korean for "Really?", offers no information about a cute dog, a mermaid costume, or a secret plan. Therefore, it's impossible to create a summary following the requested structure. The transcript is insufficient to generate a meaningful summary in Vietnamese or any other language. More information is needed.