Its kind of a... dictionary dealing with fiction (movies, TV serials, books, comics, anime and manga etc.) and all its cliches, customs, character stereotypes. In quite a humorous way, usually, without sounding biased against a specific title or person. Okay, not all its explanations are worth rolling on the floor, but many, many really are. Some excerpts here:
About a specific highly prefered coup le in Naruto: (http://tvtropes.org/pmwiki/pmwiki.php/Main/FanPreferredCouple)
"Naruto/Sasuke enjoys all sorts of support and homage, especially on fanfiction.net and its ilk, even though it has already been well-established that Naruto is straight and Sasuke is homicidally insane. To be fair, Naruto's disproportionate obsession with "saving" Sasuke does raise an eyebrow or two."
I already added "homicidally insane" into my list of possible sexual preferences.... :D
About the reason for and origin of the various shorened expressions describing pairings in fiction (example: Snape/Harry=Snarry), Harry Potter: (http://tvtropes.org/pmwiki/pmwiki.php/Main/PortmanteauCoupleName)
"Some humorous-sounding portmanteau names would be Voldetrix (Voldemort/Bellatrix), Quirrelmort (Quirrel/Voldemort), Snufflepuff (what you get when you combine Sirius Black [aka Snuffles) and Cedric Diggory [who is a Hufflepuff]), and Blamione (Blaise Zabini/Hermione Granger).
Quirrelmort as a name makes good sense but is usually (and justifiably) reserved for the form Voldemort actually takes at the end of the first book and film. If you are a fanfic writer, Your Mileage May Vary as to the exact significance of the "pairing".
Then there's Snucius (Snape/Lucius). Actually, trying to get Snape into any portmanteau name comes out badly. The worst is probably Snily (Snape/Lily)... though at least it's not as bad as 'Snevans' and some opt for the somewhat nicer-sounding Lileverus.
Seville (Snape/Neville)? The ship's dynamics are appalling, but at least the name rolls off the tongue.
How about Minerverus (Severus Snape/Minerva McGonagall)?
Aaaand Ron/Snape must be... Wait a second..."
A golden point goes to the first person who will write me the last portmanteau, Ron/Snape :D
Also, if you want to know what you should do to assuredly get your Girl/Guy, here are the rules ;P : http://tvtropes.org/pmwiki/pmwiki.php/Main/HowToBecomeALoveInterest