Gallium - Melts-in-Your-Hand Metal
The chemical element Gallium does not exist in pure form in nature, but since it's so magical and badass looking all solid-to-liquid-at-the-touch-of-a-human-hand and all, of course man figured out a way to extract it from bauxite and zinc ores to use as his personal plaything. The shiny silver masses begin liquifying at 85.85 degrees F; when held on the palm and spoken to sweetly in iambic pentameter, a hunk of gallium will melt into an oozy yet glistening metallic blob in 5 to 7 minutes. At which point you can present it to a lady in exchange for a kiss. Or more preferably a handjob.
Unlike mercury and all items on the menu at Red Lobster, Gallium is non-toxic. You could probably even swallow it, as it has been incorporated into some pharmaceuticals and radiopharmaceuticals for medical applications, but I wouldn't recommend it unless there are a lot of dollars (or more preferably handjobs) attached to doing so.
All gallium available for public acquisition appears to be 99.99% pure, which trumps Ivory soap at 99.44%. It is sold by the gram on Amazon in quantities ranging from 10 to 500.
Gallium is a top Dude Novelty Gift pick.