el día que las vacas vuelen

Examples:

ES: Sí, el día que las vacas vuelen.
EN: You'll get him about the time you get your third set of teeth.
EN: Ha ha ha! Yeah, that'll be the day.
ES: Te dejaré ir tan lejos sin mí el día que las vacas vuelen.
EN: It will be a cold day in hell before I let you go that far without me.

Note: the examples for non latin scripts have a high likelihood of mistakes, we do not own any of this data and it is sourced from Wiktionary, the NLLB database and Opensubtitles. Please help us improve this by contributing correct examples. We will be working to fix this issue over time however it is a bigger issue due to the the difficulties in dealing with non latin scripts and grammatical structures(non-romantic/european languages have lower resources as well ).