Definition

1. Verb phrase:
   • To suddenly show one's bad side/true colors; to act up; to throw a tantrum: Refers to a sudden, often unexpected, change in behavior, revealing a previously hidden bad temper, stubbornness, or unreasonable attitude. It implies acting difficult, contrary, or capriciously without a clear reason.

Usage Examples

• Verb phrase:
  • Đang bình thường, nó bỗng giở chứng không chịu đi học. (Everything was fine, then he suddenly acted up and refused to go to school.)
  • Bà ấy lại giở chứng, không ai dám nói gì. (She's throwing a tantrum again; no one dares to say anything.)
  • Đừng có giở chứng ra đấy, việc này phải làm cho xong. (Don't you start acting difficult; this task must be finished.)

Advanced Usage & Nuances

• The phrase often carries a tone of annoyance, frustration, or resignation from the speaker, describing someone (often a child, a subordinate, or someone with a known difficult personality) being unexpectedly stubborn or unreasonable.
• It can describe a sudden onset of a negative mood or a deliberate act of defiance.
• "lại giở chứng": to act up again (implying a recurring, habitual behavior).
  • Nó lại giở chứng mè nheo đòi mua đồ chơi. (He's acting up again, whining to buy a toy.)

Variants and Related Words

• Trở chứng (verb phrase): A direct synonym with identical meaning and usage. "Giở chứng" is more common in Northern Vietnamese, while "trở chứng" is used nationwide.
• Giở quẻ (verb phrase): Similar meaning, but can sometimes imply a more cunning or treacherous change in behavior, not just a tantrum.
• Nổi cơn (verb phrase): To have a fit (of anger, etc.). More focused on the explosive outburst itself.

Synonyms

• Act up: To behave badly or dysfunctionally.
• Throw a tantrum: To have an angry outburst, especially like a child.
• Be difficult: To be uncooperative or hard to deal with.
• Show one's true colors: To reveal one's real, often unpleasant, character.

Related Idioms & Phrases

• Giở trò (verb phrase): To play tricks; to start some mischief or scheme. While "giở chứng" is about mood/temper, "giở trò" is about actions and tricks.
  • Nó định giở trò gì đây? (What trick is he planning to pull?)
• Giở giọng (verb phrase): To change one's tone (often to a more aggressive or unpleasant one).
  • Anh ta bỗng giở giọng đe dọa. (He suddenly changed his tone to a threatening one.)

Notes on Usage

• "Giở chứng" is an informal, colloquial expression. It is not used in formal writing.
• The subject is usually a person. It is not typically used for objects or machines malfunctioning (for that, use "hỏng", "trục trặc").
• The behavior change is perceived as negative and unreasonable from the observer's perspective.

1. như trở chứng