xkcd #3317: Gravitational Square Wave
Title text:
Depending on the energy deposition I can manage, it might also be a fun prank on the rest of the Earth.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3317/
We'd be doomed, but it'd be funny the whole time
And informative!