A simple, Apple family pancake breakfast is ruined when Applebloom goes upstairs to fetch Granny Smith's glasses and discovers something else instead. Something very, very inappropriate for a little filly. (And, apparently, Big Mac too. He can't even look at it without fainting). A very embarrassed Applejack has to come and explain to her what it means, and the situation goes from bad to worse when Granny Smith - completely accidentally - turns the tables on Applejack.
In short, everypony loses some of their innocence except Granny Smith.