Does it seem like you cum a lot every time? You might have a condition called hyperspermia, and it comes with some downsides other than making a huge mess every time you ejaculate.
When the average man ejaculates, he pumps out between 2 and 5 ml (1/2 to 1 teaspoon) of semen. This cum is composed of more than sperm; in fact, the reproductive cells produced by the testicles only make up 5% of the volume. The rest of the semen is composed of fluids produced by the prostate and its accompanying seminal vesicles up in the abdomen, providing a medium to transport and protect the sperm on their journey to whatever awaits them past the penis.
Men with hyperspermia have ejaculate volumes of greater than 5.5 ml. Only roughly 5% of men meet this criteria, though most are clustered very close to the average range. A very small portion of men cum a lot more, with volumes two, three, or four times greater than typical. Just as very large penises are very rare, men with very high volume hyperspermia are also very rare.
While it's possible for many men to pass that 5.5 ml mark by abstaining from ejaculation for a few days and "edging" by getting close to orgasm and then backing off for an extended session, what differentiates hyperspermia is that men do affected are able to cum those large volumes every time, even multiple times in a day. They may even experience genital aching if they go more than a day or two without ejaculating.
There are two basic forms that hyperspermia takes, with thick and slow-flowing semen on one end and watery and high-speed ejaculation on the other. Another defining characteristic of hyperspermia is that these men tend to produce large amounts of clear pre-ejaculate "precum" that is used to lubricate the urethra and neutralize and remaining acidic urine in the shared tube. For some men this can be highly inconvenient, as they produce large amounts of precum whenever they're aroused — fun for sexual activities, not great for random boners at school or the office.
Hyperspermia's only real upside is an impressive display when you cum. Multiple shots, especially for those that are high-flying, can be really quite the turn-on.
On the flip-side, always producing that much semen every time means cleanup is always a task and the nipple tip at the end of the condom meant to contain any ejaculate isn't nearly large enough to contain their emissions. But more importantly, hyperspermia can also have a significant negative impact on fertility, either in the form of severely diluted semen leading to a low sperm count, or over production of low-quality sperm. Poor sperm quality is correlated with increased rates of pregnancy miscarriage.
There is no known correlation with penis or testicle size and the occurrence of hyperspermia. The overproduction of the fluid components of semen is driven entirely by the prostate and seminal vesicles, and there's been no identified characteristics that's indicative of hyperspermia. There is also no way to induce hyperspermia in an unaffected man — for bigger loads they'll have to abstain and edge and hydrate like everybody else.
Management of hyperspermia is often just a matter of having additional towels on hand to assist with post ejaculatory clean up, and regular masturbation to alleviate the overproduction of semen. If you believe you may suffer from hyperspermia, it's advised that you consult with a urologist on a formal diagnosis and seek a sperm analysis test.