It's caused by a build up of dead sperm in the testes + increased nerve sensitivity. Semen consists of water, potassium, zinc, fructose, citric acid, sperm etc. Basically a lot of electrolytes that run through and around a large series of nerves (with the concentration at the tip of the penis).
When you don't jerk off, these sperm die and become carcinogenic. Which some scientists say increases your risk of prostate cancer.
But the itchiness itself, I can more than likely guarantee it's increased nerve sensitivity in your balls. The electrolyte concentration in the testes increase. This creates more intense electrical impulses. It's your bodies way of saying, "there's a bunch of dead sperm in your testes dude, and whether your jerk off or not we WILL shed that shit tonight while you're sleeping".
A lot of dudes do this no fap thing not for will power or spiritual reasons, but out of anger. Its their way of rebelling against a biology that is designed to torture them if they're not getting laid. When a man goes for xx amount of years not having sex with a woman .... and just jerking off.... he starts to think of really stupid shit. He starts to get mad. He sees his dick as worthless. Which from an evolutionary stand point, your dick is worthless if you can't get laid. When every girl you meet and greet then go off talking about insane things like psionic powers, your reproduction value falls flat on its face.
I'm sure there are dudes on here who have noticed this pattern. Cause I've seen it my whole life. Every guy whos ever told me he's gonna stop fappn.... is either a closet virgin or just really bad with women. Guys who are good with women and have access to women, don't go on no fap binges. Unless they are celebs with sex addictions and we can immediately scratch that off the list.
The way it works is like this:
1) Man can't get laid or hasn't gotten laid in a loooong time.
2) Man spends year after year masturbating to porn and very little time with an actual woman.
3) Man gets mad and ashamed (rightfully so) cause he's psychologically castrated himself. His dick may be good for watching porn, but it's worthless for real women.
4) Man subconsciously gets mad at his own biology and low reproduction value, and consciously gets mad at himself. It's a complete misprojection of anger.
5) Man creates conspiracy that if he can stop fappn, that will give him an excuse to keep not getting laid. I call this the "dry dick justification".
6) Man wakes up 1 random night with semen in his pants.
7) Man realizes he can't control his biology anymore than he can stop shitting. So he goes back to jerking off since it's more pleasurable than wetting your sheets.
-BB