Ask, cry, etc. for the moon
Definition 1 of 1
Pro Tip 1/3Figurative Meaning
This phrase is not about the actual moon. It's a metaphor for wanting something unachievable. 
She's hoping for all her problems to vanish overnight – that's asking for the moon.
Pro Tip 2/3Not Literal
Don't interpret 'the moon' literally. It stands for any unrealistic wish or goal. 
Winning the lottery to solve his debts? Sounds like he's crying for the moon.
Pro Tip 3/3Unrealistic Expectations
Use the phrase to express the idea that someone's expectations are too high. 
Expecting the two-year-old to cook her own breakfast is like asking for the moon.