Pull a Rabbit out of the Hat

Meaning:
To do something that is unexpected.

Example:
M. Night Shyamalan pulled a rabbit out of the hat with the surprise twist in “The Sixth Sense”.

Did you know?
This idiom takes a leaf out of the common magic trick and is also sometimes used to refer to a surprising solution to a problem.

Reference: http://www.usingenglish.com/reference/idioms/pull+a+rabbit+out+of+your+hat.html