In Belfast, if you enter a fast food takeaway and ask for a fish supper, the server may well ask "what's ur cawn" in a broad Belfast accent. To which you might reply "fanta". Over the years it has become commonplace to use this phrase as a greeting. So, instead of "what about ye?", you may say "what's ur cawn?".
A tight or miserly person who wouldn't want to part with there money.. can also refer to a quite and reserved person or in other slang terms, a 'dry' person