In a cutscene in Mario & Luigi: Superstar Saga, Bowletta tricks Luigi, disguised as Peach, into revealing his identity by saying "AACK! BEHIND YOU! A HUMONGOUS COCKROACH!!!"
The Monkey Island series has a Running Gag involving the phrase, "Look behind you! A three-headed monkey!" Part of the gag is that every time the distraction doesn't work, there actually is a three-headed monkey.
Subverted in the first game, where Guybrush tries this ploy to get away from some cannibals who have him cornered. They do look behind themselves...but only for a split second, not enough time for Guybrush to get away.
Escape from Monkey Island requires you use this to distract a pair of chess players so they make bad moves, thus getting them too busy arguing with each other to notice Guybrush has stolen their chess clock. One of the players is easy to distract, but the other is only distracted by the prospect of seeing Brittany, the Brainless Beauty bank teller he has a crush on.
Tales of Monkey Island lets you keep trying to distract a couple of pirates as much as you want, but eventually Guybrush runs out of ideas.
Guybrush: Look! A distraction! Pirate: Oooh! (turns to look) What's it distracting?
And later on you meet a master thief who may have the single most menacing, sarcastic indulgence of this trope to date.
In Sam & Max: Freelance Police: They Stole Max's Brain!, Sam distracts Sal by pointing and saying "Look at what those three monkeys are doing to that head!", a slight spin on a Shout-Out to Monkey Island. Appropriately, after Sal turns back around, he points out that all of the monkeys have been locked downstairs with the fine leather jackets.
The first episode of Telltale's Back to the Future has Marty doing this to Kid Tannen so he can steal his hat. It gets quite a bit of use in later episodes, too, with various victims but Marty always the perpetrator. With the exception of Episode 5, where Edna uses this to distract Officer Parker and flee when she's exposed as the speakeasy arsonist.
In Final Fantasy IX, one of Zidane's thief skills is actually called "What's That!?", and makes enemies turn around temporarily to allow for a back attack. Also, during an early battle in the game, some of the characters tell Steiner that there is a massive Bomb behind him. He refuses to believe them, and, in accordance with this trope, the bomb is actually there, and explodes in a spectacular fashion.
Subverted in Dissidia 012. After Bartz fights Giglamesh in battle, Bartz says "Hey, look at your body!" Giglamesh believes that Bartz is attempting to trick him into letting his guard down. Turns out, Bartz was actually being quite serious when telling him to look at his body, as he was growing transparent just before being sucked into the Void.
Double Subversion, in the same game, when Kefka lures Lightning's allies away when telling them that there are still more manikins out there behind them (which there actually are).
Kefka Palazzo: Really? Could it be you're...out of steam? Oh, you poor dears, I mean turn around! You've still have more manikins waiting for a chance to play!
During the fight with Ben-K's robot form in Gitaroo Man, U-1 distracts Ben by pointing and saying "Look over there!" at the start of each Charge sequence.
In the first level of Psychonauts, "Basic Braining", Bobby does this to Raz in a cutscene as part of a prank:
Bobby: I'm not stupid, you're stupid. The coach is stupid. The whole camp is stupid! (points) That thing flying at you is stupid! Raz: What's flying at me? (Bobby kicks him off a ledge) Woah! Bobby: A-ha-ha-ha-ha! Bobby Zilch's foot, that's what!
MOTHER 3 has an item called the "Made-Ya-Look." It causes the enemy to turn around, exposing their back to reduce their defence and making them waste a turn to face you again (except for Mecha-turtles). It also allows you to see their back sprite, which is essential for someone that wants to complete the Battle Record.
At one point in Chrono Trigger, the party encounters Queen Zeal's underling Dalton. He tricks the party into turning around. Then he shoots you in the back and you start a Prison Episode.
In an omake for Sonic Unleashed, Sonic and Chip are fighting over a meat bun, and Chip tries to have Sonic look the other way so he can jack it. This is subverted in that Chip is much smaller than Sonic and doesn't have the strength to wrest it away from him.
That and Sonic was just acting distracted when he turned around.
Used in Persona 4 where Yosuke distracts Rise's stalker, who threatened to throw himself in front of any car if threatened further, for 'interrogation'.
Yosuke: "Look, a Martian!"
Grand Theft Auto: San Andreas: Tennpenny has CJ at gunpoint. CJ looks over Tennpenny's shoulder and shouts his brother's name, getting Tennpenny to look away and giving CJ a chance to escape.
Super Monkey Ball 2: The I'm-not-falling-for-that-one variation is used. Aiai and friends have Dr. Bad-boon cornered in the middle of the ocean. The latter spots a giant whale approaching, and you can guess the rest.
Various "distract" abilities for several classes in DragonFable are carried out by the player's character shouting something at random at their opponent to distract them, most often some variation of this trope. Occasionally lampshaded with "Look! It's the oldest trick in the book!"
Caveman Ughlympics uses this as a battle tactic for the Clubbing event. If a meteor is passing by, the player's caveman will scream at his (or her) opponent, driving them back considerably and possibly to a ring out.
In Kingdom Hearts: Birth by Sleep, a weakened Master Xehanort resorts to this when Terra is about to finish him off. Terra, refusing to become a sucker or tempt fate, is very, very cautious as he checks to see what's behind him... only to wind up throwing that caution to the wind because of what he saw. It actually was intended to be a distraction, and he turns around to find Xehanort stabbing himself in the chest with a Keyblade, which shocks him so badly that he's able to do nothing to defend himself against Xehanort's freed heart until it's too late. Needless to say, it's probably one of the least amusing uses of this trope ever.
Shocker: How much more do you think you can take, hero? Now don't keep telling you came in here alone. Where are the others? Huh? Ms. Marvel: Right behind you. Shocker: (scoffs) C'mon! You really think... (turns around and sees the team) ...Oh.
The introduction to Interstate '82 has Groove Champion escape from being held at gunpoint with this. His captors want to know who he's told some secret. He tells them that the only person he's told is "Dan", pointing behind them. They turn around and see a bottle of whiskey branded as "Dan Jackal's", at which point he knocks over the table with his ashtray on it to create a smoke cloud and escape.
In 7 Days a Skeptic, after Angela locks John in the brig and holds him at gunpoint, he warns her that captain Chahal is sneaking up on her from behind. Since the captain is supposed to be dead, she mocks him for such a pathetic ruse and refuses to turn around. This ends badly for her, because John wasn't lying. (Made even more egregious since John was locked up and of no threat to her, so she had no real reason to not take her eyes off him.)
Pokémon Ranger: Guardian Signs does this; after beating the second boss, one of the Pokemon Pinchers say, "Hey, look! A flying pizza!" Then, the Pokemon Pinchers make a run for it while the guy that has electricity looks.
Also happens in the past story, in which after you clear all of the levels in the Ice Temple before the final level of the Ice Temple, after the cutscene of the level, Ravio wants to get into the door, but Kira says that Ravio is too young. Then Ravio says that he will have Celebi on Ravio's side, but Kira refuses to let Ravio enter the door. Ravio then says to Kira, "Hey, look! A flying pie!" Kira falls for it, and Ravio and Celebi manage to get to the door, much to Kira's surprise when she realizes that Ravio and Celebi are entering the door.
In Fable III, the player character occasionally does this as a finishing move against Hobbes. It is always effective. All the funnier because it's slowed down slightly.
The Colonel pulls this on Conker in Conker's Bad Fur Day after clearing away a crashed plane blocking a transport vessel, and it is implied that he did so in order to have Conker unwittingly participate in the war.
In Strong Bad's Cool Game for Attractive People Episode 1: Homestar Ruiner, if you click on The Cheat in the basement of Strong Bad's house, Strong Bad does this to The Cheat so that Strong Bad can kick The Cheat into the dryer. It works even if Strong Bad tells The Cheat to "turn around."
After winning the trophy and using it on Homestar Runner, Strong Bad also does this to Homestar Runner by saying, "Look at that... thing over there." Homestar falls for it, saying, "A thing? Where?" and Strong Bad hits Homestar on the head with the trophy.
The "Your shoe's untied" ploy seems to be an endemic weakness of Paladins in the AdventureQuest Worlds universe, given how many of them were defeated by opponents who told them just this.
Sonic Rush Adventure uses this before the final boss, in which Tails tricks Captain Whisker by saying, "Aha, look! There's the Jeweled Scepter!" Captain Whisker falls for it, allowing Sonic, Blaze and Tails to go save Marine.
Mega Man Battle Network 6 had Mick and Lan pulling this off on Plata the Penguin by making it seem as though Blackbeard either escaping arrest or was already parolled in order to get away from Plata (there was no other way to leave her back at the aquarium, as Plata had hopelessly bonded with Mick).
In The Sims Medieval the Spy tells people to look behind them as a distraction before pickpocketing them.
Banjo-Tooie has Kazooie doing this in the intro while Banjo and friends are playing Poker. During the game of Poker, when Banjo says that Kazooie is not getting her birdseed money, she replies, "Don't be so sure, Banjo..." Then, Kazooie points and says, "Hey! Look outside, everyone! Grunty the witch is coming!" Then, dramatic music plays as everyone else looks. Kazooie then makes her move and takes Bottles' gold and snickers. Bottles then says, "W-Where, Kazooie? I can't see her!" Kazooie then says, "Oh... Er, false alarm, Bottles. Must've been some shadows."
In Portal 2, one of the things Wheatley tries to get the player to turn around is to point out another robot plugged into the wall. Whether or not this works is up to the player.
Later in the game, Wheatley attempts this during the boss fight. Subverted in that it doesn't work.
In BlazBlue: Continuum Shift, during Taokaka's story, when Ragna tries to exit the house, Taokaka stops Ragna and challenges him to a fight and upon winning, Taokaka tells Ragna that "now you have to stay here until you're all better." However, Ragna tries a second attempt to exit the house by saying, "Wait a second Taokaka! What's that?! There's a steak flying through the air!" Taokaka falls for it, and Ragna bolts out of the house.
The homeless man in Jazzpunk, who shows up on two separate occasions, will say "You gotta look behind you" when he's run out his list of lines. Doing so — and indeed turning away from him at all at this point, which you will inevitably do if you want to continue the game — will cause him to disappear with a cartoony running-away sound effect and dust cloud.
In Pokémon Super Mystery Dungeon, when you decide to enter the mine to bring some red stones, your partner does this to the three Drilbur guarding the entrance to the mine by saying, "Hey, all you Drilbur! Look at that! A delicious-looking Apple tree just sprouted up over there!" Surprisingly, despite the three Drilbur suspecting that trick, the three Drilbur just decide to check anyway. As a result, it works, and you and your partner go into the mine.
Dizzy's Dust animation in the Guilty Gear series has her black wing Necro tap her on the shoulder to get her to look away while he knocks the opponent skyward, with Dizzy only noticing just when it's too late. The same thing happens when Necro attempts Dizzy's Instant Kill in Xrd -Revelator-, this time by firing a Gamma Ray while Dizzy looks away. This time Dizzy notices just as he's about to fire and tackles him to alter the trajectory and cause it to barely miss the opponent, though the ensuing mushroom explosion that happens in the background is enough to make the opponent SURRENDER.
Subverted in the The Witcher 3. Geralt acquires the attention of a small attachment of guards at a rock quarry that warn him to leave immediately or face hostilities. While attempting to reason with the guards, Geralt notices several monsters appear from a nearby mining tunnel and promptly warns the guard. Expressing disbelief but ultimately taking stock of his surroundings, the main guard is surprised to find that there is indeed something behind him, for which Geralt quickly dispatches.