Whistle For Meaning

(idiomatic) Ask for with no chance of success.

Example: Used other than as an idiom: see whistle,‎ for.
2009, Max Arthur, We Will Remember Them: Voices from the Aftermath of the Great War, ISBN 0297857908:
  If we wanted something we could whistle for it - but if the Australians wanted something you'd got to get it for them, or else.
2012, Joan Jonker, Walking My Baby Back Home, ISBN 075539027X:
  She could whistle for it now; she wouldn't get a penny from him even if she crawled on all fours.
2014, Tess Read, The Secret Diary of Eric Cowell - Aged 6 1/2 months, ISBN 1784182508:
  And if it was milk I was after from that environment I could clearly whistle for it.
1973, Doris Lessing, The Grass is Singing, ISBN 0435901311, page 96:
  And as for ceilings, you can whistle for them. I have lived in this house for six years and it hasn't hurt me.