Student or Learner
Your new neighbor has just moved in, he's never seen you, but he's knocking on your door, asking for some sugar. How would you define a person who behaves like this?
I agree, but is the word you're looking for something like 'Pushy'? (informal)
I mean, a person who takes liberties with others, treating them with too much familiarity.
There's also 'brazen' (which I think may have derived in some way from the now archaic 'brass neck' [to 'have a brass neck' was to have a nerve/cheek]). The word 'brazen' itself is pretty rare. The only collocations that spring to mind are 'brazen image/effigy' (where it means 'made of brass') and 'brazen hussy' (where it has the meaning you want).