Dear Rainbow Dash,
You are invited to a picnic with me on Friday. Sadly, Rarity is making us dress fancy-like, but I have convinced her to let us wear suits because then our dresses she's making us for the Fall Formal won't be ruined. I would be very happy if you said yes. Rarity might explode. Same with pretty much everyone, including our sisters.
Sincerely,
Applejack.