sure as a gun

разг.

((as) sure as a gun (тж. (as) sure as death, as eggs is eggs, as fate, as I'm alive, as I'm sitting here, as I stand here, as you're born; амер. (as) sure as God made little (green) apples или as sure as shooting))

наверняка, дело верное; неотвратимо как судьба, как смерть; ≈ даю голову на отсечение, верно как дважды два - четыре; как пить дать [выражение as sure as eggs is eggs, вероятно, искажённое, as sure as x is x; as sure as God made little (green) apples первонач. диал.]

I'll transport Tom Bakewell, sure as a gun. (G. Meredith, ‘The Ordeal of Richard Feverel’, ch. IX) — Я упеку Тома Бейкуэлла в колонию, можете быть в этом уверены.

...if we go tearing up our sheets to make Jim a rope-ladder, we're going to get into trouble with Aunt Sally, just as sure as you're born. (M. Twain, ‘Huckleberry Finn’, ch. XXXV) — ...если мы разорвем простыни, чтобы сделать Джиму лестницу, тетя Салли устроит нам головомойку, - это уж точно.

Captain Jan Pearse, as sure as I stand here, you and your breed will get your punishment of God. (J. Galsworthy, ‘Caravan’, ‘A Man of Devon’) — Бог вас накажет, капитан Ян Пирс, вас и весь род ваш, - это так же верно, как то, что я стою здесь.

If only we could get hold of the papers... But they'll have been destroyed, as sure as eggs is eggs. (D. L. Sayers, ‘Have His Carcase’, ch. 32) — Если бы нам удалось достать эти бумаги... Но ведь их наверняка уничтожат.