This story takes place during Season 5 of the show.
Out of everypony in Equestria, few have a life as mundane as Guy Pony, a window-washing earth pony with no dreams or aspirations whatsoever. Among his job, his friends, and his life alone, Guy's only area of notable interest lies with the adventures of Twilight Sparkle and her five friends.
Inspired by their heroics in saving Equestria time and time again, Guy eventually decides to take a break from his mundane life and have some fun for once. What better way to do that than by introducing himself as a villain and antagonizing Twilight and Co. to no end?
Turns out, there are a lot of better ways than that, especially when he has little to no knowledge of what being a villain actually entails. But, well, that's what he's going with.