At some point, perhaps during a terrible business seminar run by an '80s guy, you may have come across the story of a boiled frog.
According to the story, if you place a frog directly into boiling water it will jump out immediately, but if you place it in cold water and slowly raise the temperature it will not notice and remain in the water until it is boiled to death. It is used as a way of telling people to be wary of getting used to an unusual or urgent situation slowly, not noticing the danger that you are in, or by business people who have glossed over the "frog's dead" aspect to say you have to introduce change slowly if you want to be successful.
But is this really a thing? Have people actually sat around boiling frog after frog to find out?
The answer to that latter question, unfortunately, is kinda.
In the 19th Century, several different scientists did attempt to answer this bizarre question. The first was actually attempting to find the location of Kermit's soul (or frog souls, anyway) by comparing how healthy and brainless frogs reacted to being placed in boiling water. Freidrich Leopold Goltz cut out frogs’ cerebral hemispheres, leaving them (Goltz believed) with just a small part in tact. With a little left, the frogs would react when being poked, swim when placed in water, and right themselves when placed mercilessly on their backs.
When Goltz raised the temperature slowly, healthy frogs attempted to jump out of the water at 42°C (108°F) but were boiled alive anyway, as the experiment setup didn't allow for frogs to escape being boiled alive. The brainless frogs, meanwhile, remained in the water making little movement until the water reached 56°C (133°F), at which point they began making twitching movements.
Science is all about replication, and boiling frogs to death is, for some reason, no exception. Several others attempted to boil frogs at various speeds, and with various degrees of compassion towards the frogs. One, Heinzmann, who took the trouble of placing the frogs on a small cork platform so that the frog was partially submerged but could escape, found that he was able to gently heat the frogs on several occasions up to 37.5°C (100°F) without them hopping away. He didn't go beyond this point, as trials before the experiment had convinced him this was the temperature at which frogs became paralyzed before they boiled to death.
Several others were able to do the same with some frogs, though results varied by how fast the temperature of the water was raised. Of course, this doesn't mean that the idea is correct. The setup of the experiment could have prevented the frogs from escaping, or the temperature of the water could have risen too fast for the frogs to make any meaningful attempt to escape. Modern experiments have not found the same things.
"The legend is entirely incorrect!" Victor Hutchinson, now Research Professor Emeritus of Biology at the University of Oklahoma, told Whit Gibbons of the Savannah River Ecology Laboratory at the University of Georgia.
"The 'critical thermal maxima' of many species of frogs have been determined by several investigators. In this procedure, the water in which a frog is submerged is heated gradually at about 2 degrees Fahrenheit [1°C] per minute. As the temperature of the water is gradually increased, the frog will eventually become more and more active in attempts to escape the heated water. If the container size and opening allow the frog to jump out, it will do so."
Which doesn't make quite as good an analogy, but is, at least, more scientifically accurate.