(さ)せる (emotional causative)
Usage
In addition to being used to express making someone else do something, the causative form is also used to describe evoking an emotion. In this case the verb used is an intransitive verb that indicates emotion such as 「泣く、びっくりする、楽しむ、驚く」and the person in whom the emotion is provoked is indicated by を。
Examples
殴って、弟を泣かせたことがある。
I sometimes hit my younger brother and made him cry
テストで１００点を取って、母をびっくりさせた。
I surprised my mother by scoring 100 points on the test.