How to animate a character throwing their hat on the ground? I have a snowman with a hat. 
Link here: https://www.dropbox.com/s/jji57qkhwe3yhhp/robotHat3_childOf.blend?dl=0

I want to animate the snow mans hand grabbing the hat and throwing it on the ground in front of him.

How would you go about animating the hat being released from the hand and falling to the ground.
I need a simple and quick technique as I will be creating a variety of such motions.
Link to successful result; https://www.youtube.com/watch?v=kwYacsbW5Pg
Here I explain how to use Child Of constraint to make your character pick and hold his hat.

Also, give your hat Physics > Rigid Body > Type: Active. Give the ground Physics > Rigid Body > Type: Passive. At frame 0, enable the Rigid Body > Animated option of the hat and create a keyframe. The frame before he releases the hat, create a second keyframe. The moment he releases the hat deactivate Animated and create a third keyframe, the hat should fall.