Image imported from derpibooru 
Original Description:
 
I think Fluttershy is the most “appropiate” girl to wear diapers, but I have a headcanon about Pinkie too.  
I think she discovered her diaper fetish when accidentally diapered herself during the “Baby Cakes” episode.
 
And, after discovering their shared interest, Fluttershy and Pinkie have private slumber parties (just the two of them) where play videogames and board games, watch movies, eat pizza and candies, tickle until pee themselves and wear diapers…Please let me join, girls!
 
 
Traced poses from: https://twitter.com/letitmelo/status/1201842693384609799  
by Melo.