Multiplying Sponge Balls

[Magic Ben]

i already know loads of sponge ball routines but does anybody know how to do 'Multiplying sponge balls' like the one off penguin magic? :(

http://www.youtube.com/watch?v=8D5i4tBQ7O4

[AceofD]

they use a s**** its a hollowed out ball

[Charlie]

its also known as multiplying billiards.