This story is a sequel to April Fools!
Fluttershy has always stayed out of Pinkie Pie and Rainbow Dash's pranking schemes, but she decides to give it a chance when Pinkie tells her that Rainbow bailed on her last minute. For her first prank, she has to help Pinkie pull off the prank to end all pranks.
Fluttershy has to help Pinkie put hot pink tips into Sombra's mane while he's sleeping. It goes just as well as you'd expect.
Credit for artwork goes to the lovely Evehly on DeviantArt.