Looking at the past stories we've published about World Toilet Day makes me flush with happiness. I mean, just the headlines ..."Take the plunge into World Toilet Day." (That was in 2014).and ..."Oh, the places you'll go: Toilet signs try to help." (From 2018, because we can't get enough of toilet humor.) But in all seriousness, World Toilet Day is a serious event. In 2013, the United Nations officially dubbed Nov. 19 the day to "celebrate toilets and raise awareness of the 3.6 billion people living without access to safely managed sanitation" – in other words, a place to do number 1 and number 2 with dignity, without risk to your safety and without endangering others with diseases that stem from fecal matter. Indeed, each year, diarrheal diseases, which can spread via contact with fecal matter, kill half a million kids age 5 and under. Youngsters who contract these diseases and survive often are physically and cognitively stunted for life.Using the bathroom out in the open — say, in a field or street or a body of water — is a risk factor for the spread of diarrhea as well as diseases like cholera and typhoid. According to a 2020 report by UNICEF and WHO, 494 million people practice open defecation. Public health agencies are working to bring better and safer options for going to the bathroom to places that are lacking, says Laura Kallen, a communications officer for the Defeat Diarrheal Disease (DefeatDD) Initiative at the health nonprofit PATH. That includes not only toilets but sanitation systems to dispose of waste safely and water for handwashing. That 2020 UNICEF/WHO report shows that in the year 2000, only 29% of Earth's residents had access to safely managed sanitation. By 2020, the rate rose to 54%.But that still means nearly half of humans lack that basic human right. And yes, it is a basic human right to have sanitation — the U.N. has declared it thus. "The toilet is an extremely undervalued form of basic protection in public health," says Hope Randall, one of Kallen's colleagues. So why do a World Toilet Day story that shows funny toilet signs?Let us explain.There is something called "the poo taboo" says Kallen. "Because poo causes diseases, we have an aversion to talking about it." And not to put too fine a point on it, but it is kind of stinky and gross.I wondered: When Kallen and Randall are at parties and someone asks what they do ... is the phrase "diarrheal diseases" a conversation stopper?"It sure is," says Randall."Humor is a useful way to broach the subject," says Kallen. "And then make people realize this is a serious thing." Their group even ran a "Poo Haiku" contest that we covered in 2016.So there you have it — toilets can be both amusing and sobering. In the interest of edutainment, we are sharing intriguing toilet sign photos sent in by our readers. These are from public toilets around the world. And actually, public toilets (or the lack thereof) are part of the problem of access to sanitation. And it's not just in low-resource countries. Just ask a homeless person or even an Uber or Lyft driver in the U.S. how hard it is to find a public latrine when nature calls — especially during the pandemic, says Kallen. One more point — the pandemic has reminded us all of the importance of washing hands, and some of these clever signs do a nice job driving home that message.Happy World Toilet Day!Without further loo ado, here are signs sent in by our loo-yal, er ... loyal readers. Copyright 2021 NPR. To see more, visit https://www.npr.org.