Poison Spoon

Gallium is a metal that has a melting point just above room temperature (about 86F) so it can be easily cast into a bunch of different objects. However, those objects wouldn't last very long, because unlike M&M's, gallium will melt in your hand. Over the ages people have found that a gallium teaspoon makes for a nice parlor trick, as shown below.

On a morbid note, there have apparently been instances of people being poisoned by trick spoons like this, but if you're dumb enough to drink something that melted your spoon, you might just deserve it.