(formal) What do you say? What is your opinion?
Synonym: how say you
(law) When addressed to a defendant in court: how do you plead? Also, when addressed to a jury or its foreperson: what is your verdict?
Synonym: how say you
(informal)
Sometimes followed by if: how about or what about (something)?
Followed by to: do you fancy, or would you like (something, such as an activity or a drink or a food item)?
Source: en.wiktionary.orgWhat say you to such a supper with such a woman? Lord Byron