Best Friend Manual

"Howard: [to Penny] Try telling him it's a non-optional social convention. Penny: What? Howard: Just do it! Penny: [to Sheldon] It's a non-optional social convention. Sheldon: Oh! Fair enough. Howard: He came with a manual."

- The Big Bang Theory

Plots would move more efficiently if difficult people had manuals. Convenient humanoid manuals, like best friends who know all the intricacies of their personality and are looking to clear the conflict up for the sake of their friend.

Often packaged as a convenient one-liner in response to a confused/abused expression or exclamation, the Manual Moment is a dialog device. It's a short, essential insight into understanding why someone is suddenly wanting to act out a chapter of "How to Deal With Difficult People," given by someone who can get inside their head.

Its three strengths are that it establishes a meaningful relationship between the Manual and the... "Blinking VCR character"; it provides characterization for the VCR; and most importantly, it skips over the messy "coming to an understanding" process that would otherwise require awkward frustrated encounters and use up the time slot.

The Manual, usually a friend, ex-lover or family member, has already leveled up in the area of understanding that particular model of VCR. They're ready to shepherd the n00b around the traps and over-reactions into greener pastures with a simple and unintuitive insight.

Anime and Manga
"Yuusuke: You're a hell of an actor. Not everyone can pretend to laugh at their dying friends. Hiei: Friends are a crutch for the weak. I only saved you because I might need you later. Kurama: That's his way of saying 'You're welcome'. You will learn."
 * Yu Yu Hakusho: Kurama/Hiei after the gate of betrayal, to bystander Yuusuke.

Film

 * How to Lose a Guy in 10 Days has the mother let slip that Andie is the first girl Ben ever brought home. It's not exactly advice, but it's a "heads up" insight that let her see the context.

Literature
"James: You don't just wake him up! There's a procedure."
 * The Takumi-kun series has Akaike show up and dispense advice concerning Gii for Takumi.
 * Kill Time or Die Trying
 * James acts as this for Dylan, and there is also a real manual which is circulated by email amongst new Warplings.

"Brad: Isn't there a manual for him? James: It's in Chinese. Hence Chan."
 * This trope is also lampshaded for Nathan.

Live-Action TV

 * Much of the dialog in House is devoted to troubleshooting. They're not really manuals when throwing out conjectures, but House's ex-girlfriend and Wilson, and later his former team, have enough experience to strip him down sometimes.
 * Bones: Angela often provides tips on dealing with the title character.
 * Booth is also a heartwarming reversal of sorts, being a personal interpreter for the socially incapable Temperance to successfully interact with the outside world.
 * Buffy the Vampire Slayer: Riley solicits advice from Willow on how best to approach the Slayer.
 * Frequently used in The Big Bang Theory regarding Sheldon - most often to Penny, but sometimes from Leonard to the other guys who aren't quite so used to him (as evidenced by the page quote).
 * Though it should be noted that Sheldon really did come with an manual of sorts in the form of The Roommate Agreement which Leonard had to sign. It's full of various rules for their interactions.
 * Which are mostly rules that let Leonard know not to do X thing that will annoy Sheldon sufficiently to make him unbearable.
 * In many ways, this is at the heart of Scrubs. Not just with the main Heterosexual Life Partners JD and Turk, but other characters either start out close enough for this, or develop it as the series progresses.

Video Games

 * Gakuen Heaven sets characters up in neat pairs, so you don't have to reach far for the Manual. Omi/Saionji, King/Hideaki...

Western Animation

 * Kaldur in Young Justice ends up explaining Wally's disbelief in magic to the rest of the team. Kaldur is himself a practitioner, and he and Wally have known each other for years.