Look out below! Have you ever heard that you should beware of frozen pee falling from airplanes flying overhead? Well, you don't really need to worry, but next time you see a plane pass by overhead, you might want to take cover or at least close your mouth.
Do planes actually eject human waste mid-flight, sending it crashing into rooftops as solid chunks of blue ice? Not exactly, but there is something to it. This myth is actually a three-part problem.
Back in the early days of aviation, Charles Lindbergh bragged to the king of England that he would pee in a funnel and then he said, “I dropped the thing when I was over France.” Gross and rude to French people!
Modern planes were no longer dumping their pee on purpose, but the whole “blue ice” problem arose with planes from the 1970s. Airplane toilets used to basically be Port-A-Potties with bowls full of Anotec, a blue juice used to deodorize the pee and poo. A huge holding tank on the plane would sometimes leak right out of the plane, with the blue waste cocktail freezing on the plane’s exterior and busting off in chunks, falling to the ground (usually as the plane was descending) especially during autumn months. There have been reports of roofs and cars getting smashed by the falling blue poobergs. The story became so popular that shows like “Six Feet Under” incorporated it into an episode and "Mythbusters" confirmed it was a real phenomenon.
Luckily, plane bathrooms were redesigned in the '80s, eliminating the large tank in favor of whooshing vacuum toilets that used a lot less liquid and barely leaked. Unfortunately, sh*t still happens, as they say. Normally, the tank is emptied on the tarmac, not midair. But every now and then the tank leaks, causing poo and pee to rain down from the sky.
The FAA thoroughly denies that this happens, but one Long Island couple was pelted with black and green slime while sitting in their backyard and they were told it was from a plane (the FAA says it's birds, whatever). It was not blue ice, but it honestly sounds even more gross. This is not the only incident though, so leaking plane toilets is still an occasional problem. That’s enough to make you shield your eyes from planes flying directly overhead, just in case.
TL;DR: Planes don’t intentionally launch toilet water into the atmosphere, but some gets out anyhow, so you might want to rethink catching raindrops in your mouth. It's not lemon drops and gumdrops.