मुँह में राम बगल में छुरी

You use this phrase as a warning or a critique. It functions like a label for a person's character. You can say it directly about someone: Vah to muh mein Ram bagal mein churi wala aadmi hai. It works as a noun phrase to describe a specific type of 'frenemy'. You do not usually say this to the person's face unless you want a confrontation. It is best used when discussing someone's suspicious behavior with a trusted friend.

Use it when you spot a colleague who smiles at you but steals your ideas. Use it when a relative acts overly concerned but gossips behind your back. It is perfect for political discussions or office drama. If someone's kindness feels 'too good to be true', this is your go-to phrase. It adds a sharp, descriptive edge to your observations about social dynamics.

Do not use this for someone who is just grumpy or rude. That person is honest about their feelings! This phrase is strictly for the 'fake nice' people. Avoid using it in high-stakes professional emails unless you are being very bold. It is a strong accusation of character. Do not use it for accidental mistakes either. It implies a deliberate, calculated intent to deceive.

In Indian culture, the name of Ram represents the highest moral truth and purity. Chanting his name is seen as a holy act. By contrast, a churi is a weapon of stealth. The juxtaposition of the most sacred name with a hidden weapon is a powerful image. It reflects a deep societal value on 'Manasa, Vacha, Karmana'—consistency in thought, word, and deed. When these are out of sync, this idiom comes out.

You might occasionally hear Hath mein kasai, muh mein Ram-Ram, but that is rare. The 'armpit' (bagal) version is the gold standard across North India. Sometimes people just say the first half, Muh mein Ram..., and let the listener finish the thought. It is so famous that the implication is immediate. Everyone knows exactly what is hiding in that armpit!