Is 'Fill it up, will you?" correct?

Question

I seem to recall to have heard this form of making a request in an american series:

Fill it up [referring to a drink], will you?

Is it grammatically and idiomatically correct? At first it sounded a bit awkward because I would usually phrase it this say:

Will you fill it up?

Answer 1

Yes, according to this site which appears very legit, this is called an "Imperative sentence", and that form is valid:

Tag questions are sometimes added to the end of imperatives:

          Leave your coat in the hall, will you?
          Write soon, won't you?