Sweetie Belle reads a book that presents her a quesiton about her own existence, she decides to get answers out of her known ponies

On a normal day hopping along her usual path in Ponyville, Pinkie Pie has the misfortune of coming to see horrendous signs that insult her.
Whoever put the signs don't understand the consequences of their actions.
That pony simply doesn't understand the consequences.
No problem, it will all go right.