Sour grapes
WordNet
noun
(1) Disparagement of something that is unattainable
WiktionaryText
Etymology
From the Aesop's fable The Fox and the Grapes, in which a fox, unable to reach grapes he is seeking, decides that they must have been sour.
Noun
- A putting down or expression of disdain about something that one desires but cannot have.
- I think his comments about that new car are just sour grapes because he can't afford it.