You need a paper lunch bag. "Invisible ball trick" Hold the paper bag by the edge, inserting your index & ring finger inside the edge of the bag. Keep your middle finger on the outside.
Using your thumb & middle finger, flick the outside of the bag until you get good at it. Once you have that, it's just a matter of tossing an "invisible ball" in the air, then "catching it" by flicking the outside of the bag.
You can add to the trick by embellishing looking for the ball inside the bag - turning the bag upside down and patting the bottom - make it look like you're having trouble finding it, then "notice it" on the floor & pick it up, etc.