köken: Originally “met sint-juttemis als de kalveren op het ijs dansen”, meaning “on Saint Judith’s (17 August) when the calves dance on the ice”, clearly an impossible feat, it being summer.
cold day in Hell, when pigs fly (time of occurrence of an event that will never happen)
eş: na świętego Dygdy, na święty nigdy, na świętego nigdy, jak kaktus na dłoni wyrośnie, jutro w grudniu po południu
köken: Literally, “when a crawfish swishes and a fish whistles”. Compare Ukrainian коли́ рак на горі́ сви́сне (kolý rak na horí svýsne), Russian когда рак на горе свистнет (kogda rak na gore svistnet), and Belarusian калі рак свісне (kali rak svisnje).
köken: Attributed by Suetonius in Lives of the Twelve Caesars to Caesar Augustus. The kalends (also written calends) were specific days of the Roman calendar (the first of the month), not of the Greek, and so the “Greek Kalends” would never occur.