My epic fail or another silly and lazy comic.
"Derpy overhears Fluttershy talk about how great the milk from that cow is.
Derpy attempts to milk the cow for it's amazing milk.
Derpy realizes she has no hands, so consults Lyra who's always talking about these creatures with hands called humans.
Lyra refuses to help, so Derpy asks nicely as Fluttershy did.
The cow notices Derpy's mane looks like hay, and eats it.
The resulting hairdue causes a lot of negative publicity for Derpy.
She vents her frustration on the cow, similar to what she did to a storm cloud, hence the title.
Rarity explains how this all could be avoided by wearing a hat."
As it were.