I'm an 18 yr old male, stage 5.
When I rub my nipples, it causes my testicles to contract up and down. If I keep rubbing them I get this feeling as if I were masturbating. If I keep rubbing them enough, I reach a sort of climax and a feeling comes over me. My penis becomes very hard and my muscles become really tight, almost as if I'm ejaculating, but no semen comes out. However, it is both different and similar to a regular orgasm, though I have no ejaculation. However, I have, one time, almost actually ejaculated from just rubbing my nipples. When doing this, the most pre-ejaculate I have ever seen come out when I do this.
I just recently found this pleasure out about my nipples and never before knew I could get such pleasure with doing this. I don't use fantasies or porn while doing this or while masturbating.
I did a quick search on the web for this; however, there's so much bad things I couldn't even continue to read or search for what this is. If you know anything about this or may have heard a similar case with a another boy, please let me know.
The human body has numerous areas that are connected with sexual pleasure. The genitals are the most obvious, but there are other regions that have similar impact, as you have discovered. This is actually a human characteristic, not limited to just males. In fact, the arousal from the simulation of the nipples is even strong in females. That is why it is wrong to touch a woman's breasts and it is why women are supposed to keep their breasts covered. This is also why we are commanded not to sexually touch each other. "Now concerning the things of which you wrote to me: It is good for a man not to touch a woman" (I Corinthians 7:1).
The reason you produced more pre-ejaculate fluid is because it takes longer to build sexual arousal from an indirect area than directly touching your penis. Therefore, during that longer period more pre-ejaculate fluid is produced. But to actual trigger the ejaculation of semen, that is far more easily obtained by direct stimulation of the genitals. The direct stimulation causes semen from the seminal vesicles to be loaded into the ejaculatory duct, so that when you reach orgasm (the intense feeling), you shoot out the semen. It is the lack of semen in the ejaculatory duct that causes the difference in feeling.