If you ever watch ping pong on TV, you will notice that often between points, players will walk over to the net and rub a their hand on the table. I cannot for the life of me figure out why they do this! Is it for luck? Is there some rule that says they need to touch the table?

Any ping pong rule experts care to solve this mystery?

Its because of the sweat on their hand/palm.
They rub it on the table to dry their hand/palm.
Why they dont rub on their shirts or pants? Its because their shirt or pants are wet too.
Why its near the net? Its because its the least played area on the table.
If you rub it near your end side of the table, the wet part on the table might affect the spin or play of the ball.
Why dont you use the towel to dry your hand? You have to ask for permission from the referee to go to the towel area and if you do that every time between points it will delayed the game. The referee at their discretion will allowed or not allowed you to use the towel during the game.

Very well said, B! Do you play?