Р-71

КОГДА (ПОКА) РАК (НА ГОРЕ) СВИСТНЕТ highly coll Isubord clause adv

in the very distant future if at all, probably never

when hell freezes over

on a cold day in hell (in July) when pigs fly when (not until) the cows come home.

«Как i ы думаешь, когда он вернет деньги?» - «Когда рак свистнет». "When do you think he'll pay me back9" "When hell freezes over."