This story is a sequel to Pink Is Your Color
After chasing Pinkie around town for coloring his mane, Sombra decides to take a nap to rest from his extreme pursuit. But, when he hasn't awoken for his afternoon walk with Pinkie, who is his assigned reformer, she decides to poke some fun at him while he's sleeping.
Meaning, she decides to take his armor and cape, then pretend to be him.