Thou shalt not covet thine neighbour's lime

There's a nasty bot going around telling authors in a comment to run a Windows PowerShell command to "make sure your IP is on the safe list" as "AO3 is going to block thousands of IP addresses". AO3 is doing no such thing! It actually is meant to panic authors (who use Windows) into running a malicious command designed to permanently delete everything in their Documents folder.

Here's the command broken down, and what it does:
Get-ChildItem: This is telling it to essentially list an entire directory.
-Path "$env:USERPROFILE\Documents\": This lets Get-ChildItem know that you want it to list your Documents directory.
-Exclude *.archiveofourown: This is put in to make you think you're reaching out to AO3. In reality, it's just telling it to exclude all files with the file extension *.archiveofourown (that is, files ending with .archiveofourown). Chances are you do not have any files named that.
-Recurse: do this for everything in the directory, including all subfolders and everything in them
|: take what you've got so far and use it with the following instruction(s).
Remove-Item: delete files/folders.
-Force: Permanently delete, no retrieving from recycle bin.

So to put it together: "List this entire directory, not including anything with the file extension .archiveofourown; we want to look at all subdirectories and files as well. Take this listing and delete everything permanently." And needless to say, your computer will do this without asking you if you are sure!

The big thing to take away from this is Never, ever run a command you don't understand!