Stressfree

1   weight 6 ping pongs with another 6 ping pongs. see which side is heavier5 F$ x4 _# J1 q$ ~% F$ E5 p( j8 o
2   spilt the heavier side ping pongs in half and weight against each other$ t& a# \* N) Z) O. ~: _1 ~8 L
3   weiht either ping pongs one on one then you will know which is the heavy one.