“a bolt from the blue”
a great surprise; something completely unexpected that surprises you very much
چیزی که از آسمان نازل شده، یک چیز غیر منتظره که شما را خیلی متعجب می کند
Example 1: The news of his marriage was a bolt from the blue
Example 2: The windfall from his distant cousin came like a bolt from the blue