I am 25 years of age. I've never had sex before, but my body had been calling for it to which I have refuse to succumb because I'm afraid of getting someone pregnant or having a disease. But I heard of this misconception about having excess of sperm that it can kill. Please, I would like you to explain.
The proper time to have sex is when you are married because then you will not have to worry about whether your wife becomes pregnant or worry about getting a disease. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4).
The male body produces sperm constantly once you are past puberty. A healthy male produces about 100 million sperm cells per day. Each time you ejaculate, you release about a half billion sperm cells in your semen. But all those sperm put together would be just a very small drop. What many people call "sperm" is actually semen. There is sperm in your semen, but it is just a small part of the liquid you ejaculate. The bulk of the liquid is produced by two glands called the seminal vesicles.
Just as the testicles produce sperm constantly, the seminal vesicles are constantly producing more semen. Semen contains a lot of sugars and has a limited shelf-life, so your body gets rid of the older semen through ejaculations replaces it with newer semen. For a married man, ejaculations come through sex, but before you are married you have ejaculations either through wet dreams or by masturbating or both.
The seminal vesicles have limits on how much semen they can hold. As they get full, your desire for sex increases. Eventually you either masturbate or have a wet dream, which is masturbating in your sleep. If you try not to ejaculate, it will eventually come out, whether you are ready or not. Just like you can't stop yourself from peeing, you can't stop your body from ejaculating semen. Therefore, having excess semen won't kill you, though it may embarrass you to death if it came out at an awkward moment.
The problem many men have is that ejaculating feels so pleasant that they chase after it for the sake of the pleasure. To encourage themselves to ejaculate more often than they need to, they look at pornography or think lustful thoughts to excite themselves so they can ejaculate. This type of behavior is morally wrong. "For this is the will of God, your sanctification: that you should abstain from sexual immorality; that each of you should know how to possess his own vessel in sanctification and honor, not in passion of lust, like the Gentiles who do not know God" (I Thessalonians 4:3-5). See A Look at Pornography for more on this topic.