Or, to be more precise, practical spoon-melting. Do you know about a de-lite-ful little trick that some scientists like to play on one another that causes a spoon to melt in hot liquids? Did you know that once it caused the victims to fill themselves with mercury?
Really, there's nothing like a scientist to take a wonder of the physical world and make it into a joke — and a deadly joke, at that.
The discovery of the metal known as gallium was foretold by no less a mind than Dmitri Mendeleev, who you might know from a little thing called The Periodic Table of Elements. Mendeleev used his table to predict the qualities of quite a few elements, including one that would be a metal that had a ridiculously low melting point.
A few years later, Paul Emile Lecoq de Boisbaudran discovered exactly that — and called it gallium. (Some say even the name of the element was a joke, as coq is rooster in French and gallum is rooster in latin.)
Right now, gallium is being studied for biomedical use. Apparently in can be taken up by some bacteria in place of iron — but soon the bacteria lose the ability to take in oxygen and die. So it has some potential as a powerful infection-fighting element. More importantly, though, it's a way to screw up a person's tea time. Gallium, it was soon discovered, melted when it hit about 85 degrees Fahrenheit Scientists would form spoons out of gallium and give them to colleagues, who watched as their spoons dissolved the moment they put them in their tea or coffee. Oh, how they laughed!
Unfortunately, gallium often discolored the hands and cups of the person doing the stirring. That's going a bit far for a harmless prank, so both scientists and companies — which had by this time picked up on the joke and were marketing it — looked for different formulations. What they found was a combination of metals, including cadmium, which is generally radioactive, lead, which takes out the brain bones and heart, and — to give it that lustrous shine — mercury. These poisonous spoons were shoved into the hands of brilliant scientists and vulnerable children for years, because why give up the joke? It took a while, but eventually people at large began to see giving someone a spoon made out of these things as an attempted murder rather than a harmless prank, and the gallium spoon returned.
There are still "disappearing spoons" sold as pranks. Some of them today are made from gallium, while others are made from indium, bismuth, and tin. I would still advise against drinking any tea that was stirred with such a spoon. If you do drink, though, please let us know how it goes.