What’s yours?

What'll it be?

What (food or drink) would you like to order? A: "Hi folks, sorry for the wait. What'll it be?" B: "I'll have the steak, please, and he'll have the burger." A: "Hey Tony, good to see you. What'll it be?" B: "Just the usual for me, Tom." A: "Whiskey and ginger ale, coming right up."
Farlex Dictionary of Idioms.

What’s yours?

interrog. What (or which) do you want? (see also What’ll it be?.) “What’s yours?” said the bartender.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • What’ll it be?
  • What'll it be?
  • What'll you have?
  • Make mine
  • make mine (something)
  • same again
  • (the) same again
  • blaze
  • blazes
  • blazing