There is a cheating phenomenon in lottery tickets: select a few specific table tennis balls to draw a lottery and plug them with heavy objects. Why is this cheating?

Because the table tennis lottery is to stir the table tennis through the lottery machine, a table tennis ball will fall into the gap at the bottom of the lottery machine after a while. Because table tennis is light and elastic, normal table tennis often "bounces" into the gap through stirring and ball-to-ball interaction. If you don't cheat, the probability of bouncing in is random, but if there are heavy objects in a table tennis ball, it is easy to "sink to the bottom". According to the law of conservation of momentum, heavy table tennis will be subjected to external forces.

You may not be particularly clear about this, so I suggest watching pictures of lottery machines and videos of lottery tickets.