throw someone a curve

Etymology
From the curve ball in baseball, where a spin is employed to adjust the path of the ball unexpectedly.

Verb

 * 1)  To surprise; to introduce something unexpected or requiring a quick reaction or correction.
 * He really threw me a curve when he asked me a personal question at work.
 * He really threw me a curve when he asked me a personal question at work.

Translations

 * Spanish: pescar en curva (a alguien)