Boink

From JuggleWiki

This is a funny little basketball juggling stunt that 'SzejnaMat' does at YouTube:

Real balls would be bouncing the one ball back and forth on contact, of course,
but the animator has to show it landing in the hand.

A similar stunt, often done with normal stage balls, is to collide two balls that return to each hand:

Again, the animator cannot show the balls bouncing from each other the way you know they would.
If the balls continued across, it would be like the '4x' versions of One Up Two Up Variations.

---