Oh dear,
That means something is wrong with your testicles (balls). The only normal thing that will happen to a guy is thinning of your semen (not as thick as a non-frequent H2O pistol player).
Best to consult your doctor (female is possible).

But seriously, other harm maybe reduce of sensitivity of your penis which in turn reduce enjoyment during " real thing" (intercourse). Too much may also causes blistering of your foreskin (if you are not circumcised yet).

Other then above, it is a stress relief for some and a sport for someone. Maybe in near future this sport can be introduced in the Olympics. Then definitely we can surely have our own home-grown sport man or woman to represent Singapore.

No more relying on foreign sperm.... I mean talent..
