Everybody pees. But that doesn't mean everybody has a perfect grasp of how, exactly, it works.

There are many mystifying aspects of urination — starting with what color your urine should be, how long you can safely hold it for, and if "breaking the seal" is a real thing.

With this in mind, I spoke to NYU urologist Benjamin Brucker to ask some of the most pressing questions about peeing.

1) At least 5 different parts of your brain are involved in peeing

As your blood gets pumped through your kidneys, the organs collect excess water. At the same time, they also filter out a few different types of waste: a molecule called urea (made up nitrogen, a byproduct of your cells' metabolism), chloride, sodium, potassium, and creatinine.

All this flows into a small muscular sack: your bladder. "The bladder is made up of lots of different muscles, cells, nerve endings, and blood vessels," Brucker says. "The desire to urinate comes mainly from stretch receptors in the bladder that send a signal to the brain when the bladder reaches a certain size, telling you it's time to urinate."

Recent research using MRIs has shown that this communication system is fairly complex: the signal is processed by five to seven different areas of the brain, which send a signal instructing your bladder muscles to contract and your urethral sphincter (a pair of ring-shaped muscles that allow urine to flow from your bladder to your urethra) to relax.

"This system is why humans are capable of being continent — why we're not just immediately peeing whenever we need to pee," Brucker says.

2) Your urine doesn't actually need to be clear

There's a widespread belief that, ideally, your urine should be perfectly clear at all times — a sign that you're well-hydrated. In reality, however, having totally clear urine may be a sign that you're actually drinking too much water.

"Generally, if someone is well-hydrated, the urine is going to be on the clear side, and if they're less hydrated it will be darker," Brucker says. "But it's a myth that you should always be super well-hydrated and peeing clear. For most people, I just say, 'Drink when you're thirsty.'"

Doctors generally recommend that your urine is either a "pale straw" or transparent yellow color, although it's not a huge deal if it's a bit darker or lighter (unless you have a condition that requires you to be especially well-hydrated at all times). Other colors — like pink, red, orange, or green — could be a sign of a kidney or liver disorder, or could just be the result of food coloring in something you ate.

3) Your bladder can hold about a soda can's worth of urine

Despite how long you might pee for after holding it for a while, your bladder might be smaller than you realize.

"Some people have bigger bladders, some people have smaller ones, but usually an adult bladder can hold somewhere between 300 and 600 milliliters," Brucker says. "For a comparison, I often liken it to a can of Coke."

For people with various bladder, kidney, or prostate conditions, this can vary widely in both directions.

4) Holding your urine for a long time isn't unhealthy

While it's generally a good practice to go when you need to, when the occasion calls for you to hold it for a little while, it probably won't do you any harm.

"Urinating at normal intervals — say, every four to five hours — is probably healthiest," Brucker says. "That said, in a normal, healthy patient with no medical issues, would you really do harm to your body by holding it for a while? You probably wouldn't."

It's definitely a myth, meanwhile, that holding it too long can make your bladder burst (unless you recently had a bladder reconstructed from other body tissue due to bladder cancer). There also isn't evidence that holding it for excessive lengths of time increases the risk of UTIs (more on those below).

5) Urine isn't sterile — and you should never, ever drink it

Under both normal circumstances and dire straits, it's an absolutely terrible idea to drink your own pee.

The reason is twofold. One is that contrary to popular belief, urine is not sterile. Drinking it puts you at risk of infection from the bacteria living in it.

The second reason is that apart from water, everything else in urine is waste that your body is trying to get rid of. Normally, that just constitutes 5 percent of urine, but if you're dehydrated, it'll make up a greater percentage. Taking in too much urea and other waste further dehydrates you and puts you at risk of kidney failure, as the organs work to filter out double (or more) the usual amount.

it's a terrible idea to drink your own pee

Though there are several different miraculous survival stories that involve someone drinking their own urine, most survival experts — along with the US Army's survival manual — do not advise trying it.

Additionally, from time to time, people have advocated drinking one's own urine as a way to treat several different diseases, including cancer. The American Cancer Society, however, confirms there is no evidence that drinking urine is an effective way to cure cancer.

Finally, there's the somewhat related idea that if you get stung by a jellyfish, urinating on the site of the sting is an effective remedy. As it turns out, this is a myth popularized by an episode of Friends — and scientists agree that it probably wouldn't be effective.

6) There's no evidence that peeing after sex prevents UTIs

Both women and men can get urinary tract infections, but women get them much more often for a basic anatomical reason: Their urethras are shorter and are located much closer to the anus, allowing bacteria to more easily jump from one to the other and travel up the bladder. Typically, this occurs with E. coli bacteria, though in about 5 to 10 percent of cases, it's Staphylococcus.

Unfortunately, the activity that actually spreads the bacteria most often is sex — in pre-menopausal women who are sexually active, researchers estimate sex is to blame for about 75 to 90 percent of UTIs. Using a diaphragm or a spermicide makes someone more likely to contract a UTI, but despite conventional wisdom, there's no evidence that peeing or taking a shower after sex, using condoms, or using a birth control pill makes them any more or less likely. There's some evidence that drinking cranberry juice can help prevent them, but the effect seems to be small.

A dose of antibiotics is usually effective in controlling an infection but rarely wipes out the bacteria entirely: 44 percent of women have a second episode within a year of being treated for an initial one.

7) You can train yourself to not need to urinate as often

"I see a lot of patients with complaints of frequent urination, or overactive bladder," Brucker says. "But a lot of the time, it's just a matter of them breaking the habit of peeing every opportunity they have, because then they end up peeing 25 times per day."

Simply holding it for a bit instead of going the second you feel the need to pee will gradually strengthen both the mental communication circuit responsible for keeping your bladder from emptying and the actual muscles that let you do so. (It's probably a myth, however, that holding it stretches your bladder so that it can accommodate more urine in the future.)

if all else fails, there's a secret move you can whip out in dire circumstances

If you're stuck in a situation where you do need to hold it for an especially long time, there are some things you can do. WikiHow's exquisitely illustrated guide has some interesting tips: It's good to cross your legs if standing, but not if you're sitting (because raising your thighs at all towards your abdomen will increase pressure on your bladder). Don't move too much, don't drink anything, and try to think about something totally unrelated to your overwhelming urge to pee.

If this all fails, there's a secret move you can whip out in especially dire circumstances, though it requires advance preparation. It's called the knack maneuver, and both men and women can develop the ability to execute it by doing exercises similar to Kegel exercises over time. Essentially, you try to squeeze the muscles that make up your pelvic floor, then intentionally cough or pretend to sneeze (here are some tips on how to locate and contract these muscles).

Over time, doing multiple reps of this exercise will strengthen the muscles. Then if you contract them when you do need to pee, Brucker says, "it essentially sends a signal to your brain that it's not a good time to urinate, which then sends a signal back down to your bladder."

8) "Breaking the seal" is not a real thing

A common urinary myth holds that if you're drinking heavily and ignore the urge to pee, you can stop your body from producing as much urine. Once you give in and "break the seal," however, your body will produce much more urine, and you'll inevitably have to go over and over again.

It's a nice turn of phrase, but there's no evidence this is the case. Brucker has a more scientific explanation for it. "Let's say you've been out in the sun all day, and you don't have to pee, and then you go to the bar and have four or five beers," he says. "All of a sudden you're more hydrated, and alcohol is a bit of a diuretic, so you'll be making even more urine. As a result, once you start peeing it's probably just going to keep happening."

In other words, you have to urinate over and over simply because you keep drinking — not because you went that first time. And a given volume of alcohol typically leads your body to produce more urine than the same amount of water, exacerbating the problem.

9) Alcohol and caffeine make you pee through different mechanisms

Alcohol and caffeine are both diuretics, but they work through entirely different mechanisms.

Alcohol messes with your body's production of a hormone called vasopressin (sometimes called anti-diuretic hormone). Normally your brain's pituitary gland secretes this chemical, which tells your kidneys to filter less water out of your blood, thereby producing less urine. Alcohol, however, interferes with the secretion of this hormone, so a lot more water ends up in your urine — and you need to urinate more often. Drink enough alcohol (and not enough water) over time, and you'll get dehydrated, which may be one of the ways alcohol causes hangovers.

alcohol messes with your body's production of a hormone called vasopressin

Caffeine acts as a diuretic in a different way. When it enters your bloodstream, it alters activity inside your kidneys — ultimately causing them to filter greater levels of sodium out of your blood. This causes more water to flow out of your blood through osmosis, producing more urine.

However, there's reason to believe that caffeine is a far less potent diuretic than alcohol. Controlled experiments have shown that amount of caffeine found in tea, soda, and coffee — in other words, the amount of caffeine you'd consume in most in realistic scenarios — doesn't substantially increase urine production or dehydrate people, and also that people who regularly drink caffeine develop a tolerance to its diuretic effects. In other words, for caffeine to actually make you have to pee more, you have to drink a whole lot of it.