The Powder Toy

The average human body emits roughly 180 positrons every hour from the decay of potassium 40. These positrons quickly encounter electrons and annihilate into a pair of gamma rays.

I am made of stabilized positronium. Because positronium atoms do not contain a nucleus, the neutrons have nothing to bond with, so they simply pass through without harm.   The next user has mol...

Good thing there is an entire star between me and the supernova that acts as shielding from the blast.   The next user has all of the atoms in your body spontaneously undergo nuclear fusion.

Fortunately, I happen to have a rocket powered by matter-antimatter annihilation reactions. I activate the engine, and fly away from the star.   The next user is an antimatter human who is trapp...

Fortunately, it turns out that I can survive without chocolate, so I don't go insane and nothing else happens.   The next user is floating in the center of an intergalactic void. There is n...

Good thing I am made of liquid helium, which has no freezing point under standard atmospheric pressure.   The next user is a piece of sodium that has been thrown into water.

I manage to teleport away from whatever monstrosity was hidden behind that redaction. In addition, I left behind a gram of antimatter, which causes a 25 kiloton explosion.   The next user was a ...

Fortunately, I have an experimental device that converts mass to energy. I am it at the black hole, which causes rapid acceleration of its evaporation via Hawking radiation. Since small black holes e...

Fortunately, it turns out that there is a black hole nearby. Thanks to the black hole's gravity, the railgun's projectile misses me, and falls into the black hole where it is destroyed. &nb...

If it's a stellar mass black hole, you will be shredded by tidal forces created by the black hole's gravity. If it is a supermassive black hole, then you fall inside, only to be completely ...