Truly Immovable Rod
The Truly Immovable Rod (also called the Universal Stillpoint Rod) is a meme derived from a fa/tg/uy's story about how his dickish DM applied some very dodgy physics to an Immovable Rod, judging that it remained immutably fixed in the universe while the planet they were on was moving (and thus setting it off, relative to the players, at several thousand miles an hour when activated). The very same fa/tg/uy later used an Immovable Rod as a siege weapon to destroy a castle, pissing off his DM.
It was considered that, since every celestial body is moving very quickly, anybody who placed such an Immovable Rod would never see it again, as their system left the stationary rod floating in the void. If this had happened a lot, there could be any number of Immovable Rods out there, simply biding their time until some unsuspecting and unfortunate planet happens to pass through the same region of space an*CLANG!*
WHAT THE FUCK WAS THAT?
Oddly enough, this was exactly quoted in Lucifer's Hammer, a book written by Larry Niven and Jerry Pournelle. In 1977. When a space station orbiting the Earth was suddenly hit.
Dickish GMs who wish to avoid such shenanigans should utilize a setting that is not based on planets, but instead, on an infinite plane of existence consisting solely of land extending in all four prime directions, and without proper "space" as we know it in this crapfest universe that we type this shit in. Or to use a Ptolemean universe, with a planet in the center of the Universe that doesn't move or spin, and sun, moon, stars and planets orbiting around it. Only then will the Immovable Rod function as advertised, thus avoiding the collision of physics and magic, and consequently, rendering all attempted castle rapes using this method as invalid schlep comedy and copy-cat antics to be derided and punished with style. A final alternative is to claim it's relative to the nearest celestial body, or anchored to a manasphere a la Shadowrun.
- http://suptg.thisisnotatrueending.com/archive/1709686/ - suptg archive of the original thread.
- https://www.youtube.com/watch?v=9eKc5kgPVrA - a more scientific explanation of immovable objects.