How do you say why thank sir in Brazilian?

There's no direct translation of "Why thank sir" in Brazilian Portuguese that conveys the same meaning and tone. It's a rather informal, old-fashioned phrase that might be considered odd in Brazilian Portuguese.

However, depending on the context, here are some possible translations:

If you're expressing gratitude:

* "Obrigado, senhor!" (formal, for a male)

* "Obrigada, senhor!" (formal, for a female)

* "Valeu, senhor!" (informal, for a male)

* "Valeu, senhora!" (informal, for a female)

If you're surprised and expressing gratitude:

* "Nossa, obrigado, senhor!" (formal, for a male)

* "Nossa, obrigada, senhora!" (formal, for a female)

* "Caramba, valeu, senhor!" (informal, for a male)

* "Caramba, valeu, senhora!" (informal, for a female)

If you're trying to understand the reason for the gratitude:

* "Por que?" (Why?)

* "Por que você está agradecendo?" (Why are you thanking me?)

Remember to adjust the level of formality based on the context and your relationship with the person you are speaking to.