Leonardo DiCaprio has revealed the easiest way to scare a celebrity: by pretending to be an over-zealous fan.

The Oscar winner managed to prank his Wolf of Wall Street co-star and friend Jonah Hill by doing just that on the streets of New York City on Monday.

Surrounded by a posse of friends, DiCaprio ran up to an unsuspecting Hill posing as an enthusiastic mobile phone photographer.

Hill, who was using his mobile phone when the sneak attack occurred, was visibly terrified by the approach, before realising who was behind the camera and greeting his famous friend with a big hug.

Paparazzi managed to capture the entertaining moment on camera before DiCaprio and his party of six friends wandered off.

Watch the prank below (it starts around the one-minute mark)