oxe
/ˈɔ.ʃi/what?, huh?, wow!
The clipped form of 'oxente', fired off at the start of a reply to signal surprise, disbelief or mild indignation. It is the single most recognisable Northeastern marker in speech and instantly regional-sounding elsewhere.
Oxe, de onde você tirou essa ideia maluca?What? Where did you get that crazy idea?