Twilight Sparkle received a human history book. Somehow, the Cutie Mark Crusaders got ahold of it and it's the only thing that Scootaloo will read. The other two are just along for the ride.

Discord is aware of humans.

Takes place during Season 6. Also takes place during Legends of Tomorrow S6E4 Bay of Squids, but that really isn't super plot relevant, even if it's the sole reason for the crossover tag.

Totally legit reviews:

I guess that was pretty funny in hindsight
-The Official Cutie Mark Crusaders
★★★★★

Chaos.
-Bill Cipher
★★★★★

THAT'S NOT HOW NUKES WORK! Other than that, it was pretty funny.
-J. Robert Oppenheimer, Nice Peter
★★★★★

I'd say this is your best fic yet. Lots of jokes, great execution, and great execution, if you know what I mean
-PRUALCS
★★★★★

Now we're the new protagonists!
-King Josh MDXLVIII and Sir Stuffycheeks III
★★★★★

lmao Russian spies
-Eobard Thawne
★★★★★

I had no idea that happened. Had a good laugh at my cuz.
-Babs Seed
★★★★★

Average rating
★★★★★