curveballcurve‧ball /ˈkɜːvbɔːl $ ˈkɜːrvbɒːl/ noun [countable] 
1American English in baseball, a ball that is difficult to hit because it does not move in a straight direction2informal a surprising and unexpected action or event: 
When life throws you a curveball, you need to know how to handle it.
1American English in baseball, a ball that is difficult to hit because it does not move in a straight direction2informal a surprising and unexpected action or event: When life throws you a curveball, you need to know how to handle it.