Original letter here.

Dear Princess Twilight Sparkle:

Don't tell Button. He'll freak out.

Ah, who am I kidding? Of course you're going to tell him. So please just record his reaction so we can post it on Equestria's Funniest Home videos.

Excitedly awaiting your videos, Princess Celestia.

P.S.: I'm actually kind of jealous of her. I'm going to have to talk to my father about this.

Author's Note

Trivia: at 26 words, the original letter is one word shorter than the one for "A Bird in the Hoof", making it the shortest chapter of all.