before somebody can say Jack Robinson
(faster|quicker) than {sb} (can|could) say Jack Robinsonbefore somebody can say jack robinson
01
so suddenly or quickly that leaves one with no time to react or notice anything
Humorous
Idiom
Informal
例子
They react to changes before you can say Jack Robinson, adapting instantly to new circumstances.
He finished the race before you could say Jack Robinson, crossing the finish line in a flash.
