Put your best foot forward. Put on a happy face. Smile and the world will smile with you. In public, people tend to don their social masks, keenly aware of what society wants us to look, sound and act like and doing those things that are considered “acceptable” behavior.

In private, however, we feel more comfortable engaging in the behaviors that are frowned upon in public or what we feel are “taboo,” despite how surprisingly common these behaviors are. Check out these six “gross” habits and how common they actually are.

We Pick Our Noses

Picking your nose is unattractive, unclean and potentially harmful, but, according to a survey shared by the BBC, a whopping 91 percent of Americans may pick their noses in private. The scientific term for this behavior is rhinotillexomania, and it’s more common than you think. In a second study conducted on 200 teenagers, nearly all admitted to picking their noses, an average of four times a day. Nearly 10 percent admitted to picking their noses 20 times a day or more.

Nose picking, especially severe cases, can cause complications for the picker. Chronic nose pickers may be at risk for perforating the nasal septum, and one woman actually picked a hole into her sinus! Nose picking may help spread disease and bacterial infections. Nose pickers, for example, are more likely to carry Staphylococcus aureus in their noses than non-pickers.

We Don’t Wash Our Hands

According to an article published in The Daily Mail, 62 percent of men and 40 percent of women admit to not washing their hands after using a public restroom. A survey of 100,000 people, the largest of its kind ever performed, showed that nearly half of all women and more than half of men don’t bother with this basic hygiene staple when they think no one is looking. One company, which hopes to shame workers into better hygiene, devised a tool that tracks how many people visit office restrooms vs. how many times hands were washed, then displays the percentage for coworkers to see in real time. Within a day of the sensors being installed, hand washing rose to 90 percent and eventually tapered off to between 80 and 85 percent -- still much higher than the average.

Not only is this habit taboo, but it’s also unhealthy: the average person comes into contact with more than 10 million bacteria each day. The CDC says that hand washing is one of the most effective ways to cut the spread of infectious illnesses. According to their numbers, dirty hands contribute to 50 percent of all foodborne illness outbreaks.

We Don’t Wash Our Hair

Washing your hair is a process: you shampoo, condition, apply styling products, mud masks, deep conditioning or other beautifying treatments, then blow dry, straighten, curl or otherwise style. Unlike (most) men (there are men who obsess over every strand of their “casual messy” gelled hair for longer than it takes their partner to get ready to go out), our hair takes time and energy to style. So when we aren’t going out or when we think we can get away with it, we skip the hair washing and opt for dry shampoo, caps or ponytails to hide it.

The good news is that this habit may be healthy for your hair. Experts say that unless you have particularly oily or fine hair, you only need to cleanse your hair about three times a week.

We Bite Our Nails

Nail biting, or onychophagia, is a fairly common habit for people of all ages. About 30 percent of children, 45 percent of teenagers and 25 percent of younger adults bite their nails, although the numbers drop dramatically to about 5 percent in older adults. While this habit is less of a taboo than some others, it’s just as gross.

Your nails are an ideal location for bacteria like salmonella and E. coli to thrive. Because our hands touch so many dirty surfaces, biting nails is an excellent way to transfer the bacteria we come in contact with to our mouths, where we risk infection and illness. Warts on your fingers caused by human papillomavirus, or HPV, are common among chronic nail biters, and these warts can spread to your mouth and lips during biting sessions.

We Sleep with Our Makeup on

Up to 25 percent of women sleep with their makeup on. While we all have nighttime routines that we try to keep (brushing our teeth, meditating, or putting on lotions or creams, for example), too many of us leave makeup on our skin, either out of laziness (or late nights on the town) or, as was discovered by the Daily Mail, because women believe that they will look better for their partners if they sleep in makeup.

Leaving your makeup on while you sleep can age your skin as much as 10 years over the course of a month, the newspaper found. It can also increase your risk of infection. Experts suggest if you regularly fall asleep with your makeup on, leave a box of baby wipes by your bed. They’ll give you a quick and easy way to remove your makeup and save your skin.

We Urinate in the Shower

According to a 2014 YouGov Omnibus survey, 62 percent of adults admit to relieving themselves in the shower, although the majority of those adults say that they do so only infrequently. Only 7 percent admit to doing it on a daily basis. Perhaps the reason that people say that they only do so infrequently has to do with an earlier study conducted by the same company, which found that 42 percent of people surveyed found urinating in the shower to be unacceptable. A separate survey by the Today Show found that 75 percent of respondents have urinated in the shower.

Like skipping showers, this is another “gross” habit that actually seems to benefit to our wallets and the environment. Toilet flushing consumes about 27 percent of indoor water use. And unless you have an infection, urine is sterile and non-toxic. So go ahead, save the planet and urinate in the shower!