The most fucked-up, mentally scarring fanfiction you will ever read. Also happens to be about My Little Pony. The plot:
Rainbow Dash goes to see her friend Pinkie Pie. Pinkie makes her eat a cupcake, which makes Rainbow fall asleep. When she wakes up, she's strapped down in Pinkie's basement (which is filled with other pony's body parts, made to look like they're at a party) Pinkie then proceeds to skin Rainbow's cutie mark off, cut off her wings, EAT PART OF RAINBOW'S LEG- etc. Rainbow eventually dies and Pinkie puts her in a cupcake.
I just read the Cupcakes Fanfiction. I will never eat a cupcake again without throwing up.