Summed up as the Nazi Space Pirates Crusade against the Communist Republic of Bananas, written by a guy with too much time and too little to do, on the continent of Equestria, with clichés in love stories, gangsters, cowboys, superheroes, etc…, and the final pursuit of the be all end all, Soup.

Spike learns from Magnum, Rarity's father, that she loves mustaches. So in order to impress the one he loves most, Spike sets off on a quest of epic proportion, meeting every mustached character in the series so far! Whether its under the teachings of Steven Magnet or a showdown with the FlimFlam brothers, Spike will do whatever it takes to reach the lost spring and obtain the greatest mustache of all time!
Just a note: I am taking some ridiculous liberties with character like the The Dude Lebowski, as well as others.