"Well, Ponyville's a small place, so mostly we just go talk to other ponies? Or if they live in another city, we can send a letter to them. And Spike can send letters to Princess Celestia personally, so anytime we need to sent her something we can do it with him."

Rainbow was not intentionally providing absolutely no context as a demonstration of what all these weird terms and phrases did to her own head... no matter how well it worked like that in practice.