They do it to save time and they aren't the only ones who use them voluntarily

Most toddlers can feel a sense of accomplishment when they graduate to the big boy or girl potty, but some people in Japan voluntarily going back to wearing diapers.

Japanese media report the trend of wearing adult diapers is becoming increasingly popular, especially for women looking to save time.

According to Oddity Central, Japanese magazine SPA described the trend in an article titled "The Ultimate Form of Slob." In the article they talk about the masculinization of women who don't clean their rooms as often as they used to, don't shave and wear diapers.

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One 25-year-old woman, who would only be identified under a pseudonym, has been wearing a diaper to work at a real estate agency almost every day for the last six months. She does it to save time and the trouble of going to the washroom. She doesn't wear one when she's with her boyfriend and only wears them under a skirt because pants make it too obvious.

This woman is far from alone. Sales of adult diapers surpassed sales of diapers for babies for the first time in Japan this past May. However, a big part of this is Japan's quickly aging population, meaning there is an increasing number of people who require the diapers.

As a Bloomberg article points out, companies are rushing to get the biggest share possible in this booming market.

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Japan is also doing some other interesting things with adult diapers.

In 2008, manufacturers conducted the world's first adult diaper fashion show. And used diapers are being shred, dried and sterilized to be used as fuel pellets for boilers.

Adult diapers aren't just a growing trend in Japan, they are also a tactic for gamblers. Casino-goers wear them so they don't have to get up to go to the bathroom and abandon their slot machines.

Tim Pelton, a professor at the University of Victoria's Centre for Addiction Research, learned of the trend from casino staff when studying signs of problem gamblers. Casino staff constantly walk the floors and see the diapers peeking out of people's pants and can smell the odour.

According to Digital Journal, in 2007 an Ontario company began selling adult diapers online. They hold nine cups of fluid, dry within an hour and are reusable.

(Photo courtesy Getty Images)