expression
do not be surprised; lo and behold; wait for it
A set phrase used to preface a surprising or unexpected statement, often with a dramatic or rhetorical tone. Equivalent to 'believe it or not' or 'you won't believe this, but...'.
驚くなかれ、彼はその試験に満点を取ったそうだ。
Lo and behold, I heard he got a perfect score on that exam.
驚くなかれ、この小さな町に世界的な企業の本社がある。
Wait for it—this small town is home to the headquarters of a global corporation.
From the classical prohibitive form of 驚く (odoroku, 'to be surprised') with the auxiliary なかれ (nakare, 'do not'). The phrase is a fixed expression in modern Japanese.