Bill: (on being incompetent fathers who use incompetence to get out of chores) You see, we are dumb, but we're not so dumb.
Captain Jack Sparrow, Pirates of the Caribbean. You might think he's quite a harmless fellow when you lock him in chains, but if you start a 10 minute long conversation with him, he'll probably talk you into opening his chains, steal your pistol and threaten you with it, make a break for it and steal the ship you should be guarding before you can even realize what the hell just happened. And when you reach out for your pocket to get the whistle and call the guards you'll notice that your wallet is also missing...the quotes below give great examples:
Norrington: "No additional shot nor powder, a compass that doesn't point north...(looks at Jack's sword) And I half expected it to be made of wood. You are without doubt the worst pirate I've ever heard of."
Captain Jack Sparrow: "But you have heard of me." —>(Shortly after, when their ship is stolen by two people, including Jack)
Lt. Groves: "That's got to be the best pirate I've ever seen."
Ragetti, who is revealed to know more and more as the movies go on.
Although, given that he seems really uneducated and unable to read, he just might have a knack for insightful comments.
Lack of book learning is not always a symbol of stupidity, especially not in the time period of the films.
Part of the joke is how many obscure bits of trivia he knows (like the proper pronunciation of "Kraken" in the original Scandinavian) despite being completely illiterate.
James Kirk in the new Star Trek film practically turns this into an art form, frequently acting like a womanizing idiot or playing the fool throughout parts of the film.
However, it quickly becomes clear that he's not nearly as stupid as he leads people to believe, effectively beating the supposedly unbeatable Kobayashi Maru through rather ingenius means and then stopping Nero's rampage of revenge against the Federation.
Prior to joining Starfleet, it's even stated by Pike that Jim's the only "genius-level repeat offender in the Midwest."
If you watch The Wizard of Oz closely, you will notice that the "brainless" Scarecrow is the one who has all the ideas, comes up with the plan to sneak into the witch's castle, and even (at the climax) manages to think quickly enough to use the Tin Man's ax to drop a chandelier on the witch's soldiers. This is even more pronounced in the original book, where he comes up with clever solutions to nearly every obstacle and monster that the Witch of the West and Oz itself throws at them. In both versions, the Scarecrow's dumb act has even fooled himself. He associates intelligence solely with being a "great brain" or "deep thinker". Since he's not one of those by any means, he fails to recognize his planning, quick thinking, and resourcefulness are also signs of intelligence.
He's so in denial of his own intelligence that he resorts to Self-Deprecation. When Dorothy points out to him that he came up with a clever plan to save her, his only response is to say that if he had a brain, he would have thought of it sooner.
Of course, that was rather the point - the Cowardly Lion and the Tin Man also always had the traits (bravery and heart) that they wanted the Wizard to grant them, which is why he gave each of them nothing more than an item to act as confidence builders.
In the musical version of Wicked, it is implied that the Scarecrow, actually a transformed Winkie prince, knew he was the most intelligent of the group, but faked stupidity so that he could join up with Dorothy and return to Elphaba.
Zatoichi, in the series of movies of the same name, posed as a harmless blind masseur (he really was blind) until it came time for either intimidation or the mass slaughter of the Evil Minions.
In at least one movie he actually can see, but pretends to be blind in order to gain a blind person's insight. Seriously. It makes more sense when he says it.
In the 2006 Pink Panther remake, it is revealed that Inspector Clouseau could speak Chinese all along and figured out who the killer was when the Chinese woman named "Yu" was brought in for questioning. His rant about actually knowing Chinese turned out to be true.
In Revenge of the Pink Panther, a character expresses the (erroneous) belief that Clouseau's blundering is actually a version of this.
Budd from Kill Bill is depicted to be a drunken redneck who works as a bouncer for a titty bar. Nonetheless he has shown a philosophical side and is the only Viper to get an advantage on Beatrix Kiddo, by faking unawareness that she's hiding around his trailer and blasting her with rock salt when she busts through his door. In fact, Budd is the only of the vipers not to be killed by The Bride (well, Elle is not actually shown dead, but is at least very thoroughly screwed).
With the recent announcement of Kill Bill Volume III, Elle Driver is confirmed to be alive.
He's also the only one with whom she seemed to exercise caution. With everyone else, Bill included, the barges in and starts swinging, kicking, and slicing. When the woman who takes on an entire army of sword-wielding Yakuza by herself skulks around a guy's trailer and takes the time to make sure he's sitting down before making her move, and he still gets the best of her...you know he's a badass.
Silent Bob, from Kevin Smith's View Askewniverse appears to be little more then Jay's silent companion, only less exuberant and dumber. It turns out that he's quite knowledgeable. Your Mileage May Vary; Silent Bob may seem smarter than Jay because his friend is very loud.
In Mallrats, Silent Bob apparently won his eighth grade science fair by turning his mom's vibrator into a CD player with "chicken wire and shit"
Yoda in The Empire Strikes Back is introduced this way, pretending to be an irritating little creature who steals food and squabbles with R2 before finally revealing himself to be the ancient and powerful Jedi master.
Jackie Chan tends to play these kinds of characters, particularly in Rush Hour, when he allows Chris Tucker's character, Carter, to believe he doesn't speak English. Carter gets him back, though, when he reveals that he can speak Chinese just fine. The Screwups Reel makes it quite clear, however, that Tucker himself can't, and since he doesn't speak Chinese in the second movie either, it's possible that Carter only knows the basics of the language or learned just enough for the prank.
He speaks Chinese in the second movie, it's just horrible. In his very first scene, he thought he was inviting two Chinese girls to have a drink, when he was actually inviting them to get naked, and sacrifice a small goat. Granted, the first part of that invitation is completely in character for him.
In both the 1940 and 1920 versions of The Mark of Zorro, Diego de la Vega plays the featherbrained fop to lull the corrupt Governor Quintero, while, as the masked swashbuckler Zorro, trying to frighten Quintero out of the country.
And the 1974 made for TV movie with the same title. Frank Langella's portrayal of foppish Diego de la Vega is the greatest bit of the film.
The janitor in the horror film Disturbing Behavior pretends to be mentally handicapped because it causes people around him to drop their guard and become "interesting."
In Dirty Rotten Scoundrels, Glenne Headly plays an extremely ditzy poor little rich girl who is an obvious target of the two cons, Steve Martin and Michael Caine. Turns out that she was counter-conning them from the beginning.
In The Usual Suspects, Verbal Kint, pretending to be a weak-willed and crippled sap who was taken advantage of by Dean Keaton, rather than the diabolical crimelord he is.
In Superman III, villain Ross Webster's assistant and girlfriend Lorelei acts the part of the Dumb Blonde but is secretly highly intelligent (when alone she reads Immanuel Kant's Critique of Pure Reason and disputes one of Kant's arguments). As a result she's able to outwit Ross and his sister.
In Horse Feathers, Connie plays up her football ignorance to try to get Professor Wagstaff to share his secret signals. She overdoes her childlike ditziness, so either he sees right through the ruse or he thinks she needs to snap out of it.
Roger Rabbit spells it out in Who Framed Roger Rabbit, and implies that obfuscating stupidity is second nature to a toon:
Roger: (to Judge Doom and the Weasels) We toons may act idiotic, but we're not stupid!
Your Mileage May Vary, but given that he never actually does anything useful in the movie, it could just be that he's full of hot air on that one, which would also just make him stupid rather than using Obfuscating Stupidity.
The toons in general seem to vary in intelligence. It could be that Roger is just a stupid one.
Subverted in The Court Jester: some of the villains, believing the title character is either an assassin they hired or a Robin Hood-esque resistance leader, believe he's doing it. In fact, he's actually a carnival performer who really is that twitchy and bumbling.
Sir Roger Moore's James Bond uses this several times.
Lampshaded in Scream 2, when Dewey claims he is using a form of this trope:
Dewey: "How do you know that my dimwitted inexperience isn't merely a subtle form of manipulation, used to lower people's expectations, thereby enhancing my ability to effectively maneuver within any given situation?"
(a brief pause, then Gale starts laughing)
Samantha "Sam" Sparks in Cloudy with a Chance of Meatballs was secretly a nerd in her school days but hides her brains behind the facade of the pretty, ditzy weathergirl for fear of being stigmatised. It adds another layer to the character that she is voiced by Anna Faris who is more well known for playing genuinely ditzy characters.
In Mr. Baseball, Tom Selleck plays an American baseball player who signs up with a Japanese team. The team's manager appears not to know English through most of the film, causing grief for Selleck's character when he finally finds out.
True Lies does this beautifully several times, though it borders on ridiculous when Harry calls the obvious nuclear warhead an espresso machine...of course at that point it's clear he was being sarcastic to annoy the terrorists.
Summer of '42 has its underage protagonist employ some of this to obtain some condoms from a pharmacist. When asked what he wants them for, he says they're actually for his (nonexistent) older brother and that he assumes they're for filling with water and dropping on people from a roof.
In Dumb and Dumber, the kidnappers only think Harry and Lloyd are doing this.
In Maverick, Bret Maverick pulls this off effectively in an early scene where he invites himself into a poker game, saying, "I promise that I'll do nothing but lose for at least an hour." For the first hour of so he indeed loses every hand. From second hour of the game on, Maverick winds up cleaning out the rest of the table. When one fellow gambler accuses him of cheating, Maverick explains, "What do you think I was doing for the first hour? I was learning your tells." This sets the tone for the rest of the movie, in which Maverick appears to be bumbling his way through the West, but in reality is as shrewd and sly as anyone else in the movie.
In a more specific example: in The Dark Knight, Joker causes chaos by threatening to blow a hospital unless the people kill a man who claims to know Batman's identity. When someone tries to ram the police vehicle carrying the man, Bruce pulls a vehicular Taking the Bullet. Afterwards he acts like it was an accident, but still shoots a knowing glance towards the man whose life he saved.
Gordon: That was a very brave thing you did.
Bruce: Trying to catch the light?
Gordon: So you weren't protecting the van?
Bruce: Why? Who's in it?
Bruce: (after shooting the knowing glance) Do you think I should go to a hospital?
Gordon: You don't watch the news much, Mr. Wayne.
The Hallelujah Trail: Walks Stooped Over, the Sioux chief who does all of their negotiating in badly translated sign language, is revealed at the end as speaking perfectly good English.
Both Mr. Green and Colonel Mustard both embody this throughout most of the film Clue.
