kad na vrbi rodi grožđe

Serbo-Croatian

Etymology

Literally translates as "when willows bear grapes"; the phrase stems from folklore where willows are depicted as commonplace but unfruitful trees.

Idiom

kad na vrbi rodi grožđe (Cyrillic spelling кад на врби роди грожђе)

  1. (idiomatic) when pigs fly; never