骂街 is a colloquial separable verb (离合词) meaning 'to shout abuse in the street' or 'to curse publicly in a loud, dramatic way'. It carries a strong folk-cultural flavor—picture someone standing in the street hurling insults, a scene often associated with traditional Chinese neighborhoods or marketplaces. As a separable verb, measure words or modifiers can go between 骂 and 街: 骂了一天街 ('cursed in the street for a whole day'). The object 街 literally means 'street', so the image is 'to curse the street'—i.e., to curse at everyone in public.