Updated: Mar 13, 2021
für die Katz sein
phrasal idiom: to be in vain
This idiom literally translates as ‘to be for the cat’. If you consider the tendency of cat owners to buy fancy apparatus for their cats, only for them to end up being more interested by the cardboard boxes they come in, you can see how the idiom means ‘to be all for nothing’ or ‘to be in vain’. The phrase can also mean ‘to be a waste of time’.
If you are interested in the more likely origin of this idiom (a fable by Burkard Waldis: “The Blacksmith and The Cat”), have a look here.
War denn wirklich alles für die Katz? = Was it all really in vain?