History Main / OnceForYesTwiceForNo

* In a ''Literature/TheBabysittersClub'', after Claudia's grandmother Mimi has a stroke, they are relieved to realize that she can still communicate this way.

* Bumblebee in the ''Film/{{Transformers}}'' films can only communicate by tuning his radio to different stations.

* Creator/DickKingSmith's book ''Ace'' is about a pig named Ace who has the unique natural talent of understanding everything humans say, and works out a way of communicating with farmer Ted Tubbs by grunting once for "no" and twice for "yes." He briefly ponders expanding on it by devising specific meanings for three grunts, four grunts and so on, but ultimately decides this will get too complicated for them both.

* ''Series/SuperiorCourt'': An episode of this 1980s courtroom drama had an episode where a witness, rendered a vegetable after a game of Russian roulette, testify at a murder trial by answering yes/no questions through blinking. His testimony helps convict the defendant of reckless use of a firearm. [[spoiler: The post-script is tragic: The young man dies shortly after the events of this episode.]]
* Captain Pike, in the ''Series/StarTrekTheOriginalSeries'' episode "The Menagerie," is so grievously injured by an accident that he can only communicate by making his specialized wheelchair beep, once for "yes" and twice for "no". At one point he's found repeating "no" over and over again to warn of something he has learned.
* The nebula alien in an episode of ''Series/StarTrekVoyager'' communicates with the crew via the limited phrase book of the ship computer.
* In the ''Series/StarTrekTheNextGeneration'' episode "Darmok", an alien tries to communicate with Picard using a language comprised solely of metaphors. In practice (and to keep the audience from getting confused), this involves trying to communicate using only a handful of phrases over and over.

* The early-90's UK kids' show ''Series/{{Woof}}'' has this when the main character becomes a dog.
* An episode of ''Series/TheOddCouple1970'' has a "seance", where Oscar plays a joke on Felix by doing the knocks (in another room), pretending to be the ghost of the previous tenant.

* Crichton invokes this in an episode of ''Series/{{Farscape}}'' in order to communicate with a DRD. He even calls it the ''Star Trek'' method and names the DRD "Pike".
* This is used in ''Series/{{Community}}'' with Abed and a Secret Service agent [[StalkerWithACrush keeping tabs on him]], reversed so two car honks is yes.
* In an episode of ''Series/FullHouse'', Jesse asks ''Wake Up, San Francisco'' co-host Rebecca Donaldson on a date. She gives him her answer by winking on the show the next day, with one wink for "yes" and two for "no."
* Jack the dog in ''Series/TalesOfTheGoldMonkey:'' barks once for "no," and twice for "yes." And he's always right.
* ''Series/BreakingBad'': Hector "Tio" Salamanca is confined to a wheelchair and unable to speak in his old age (possibly from a stroke). He presses a bell attached to his wheelchair arm once for "yes" and does not press it for "no." This unusual method of communication is used for several humorous scenes as he tries to convey his meaning to other characters but is sometimes used more dramatically, as he reveals he knows more than his senile appearance lets on.
** Most dramatically in the season 4 finale, when [[spoiler: Walt connects a bomb to the bell. When [[BigBad Gustavo Fring]] arrives to kill Hector with a lethal injection, Hector activates the bomb by rapidly pressing his bell, instantly killing himself and [[ScaryBlackMan Tyrus]] and fatally blowing half of Gus's face off]].
* ''Series/{{CSINY}}'': Mac inverts it twice.
** "Blink," the pilot episode, has him using this with a woman suffering from locked-in syndrome. Since she can't move anything but her eyes, Mac asks for two blinks for "yes" and one for "no." Unfortunately, she has a stroke before he can finish questioning her.
** He inverts it again in season 7's "Damned If You Do," only he asks a very badly beaten woman to move her finger instead of blinking.

* In the ''Series/{{Supernatural}}'' episode [[Recap/SupernaturalS09E01IThinkImGonnaLikeItHere "I Think I'm Gonna Like It Here" (S09, Ep01)]], Dean has Crowley locked in the trunk of the Impala. He asks Crowley to knock once for yes and two for no and then asks Crowley if he is alive.

* One episode of ''{{Series/Andromeda}}'' has Dylan sending a message to the ship, ordering them to arrive at his location. Tyr remarks that, judging from the increased blinking, there is something he's not telling them. Rommie counters by saying he ''does'' - the blinks are a High Guard CovertDistressCode.
* ''Series/{{MASH}}'': The compound is besieged by artillery fire (and friendly fire at that), during which the officer's latrine gets hit with Henry in it. As the docs and personnel gather at the scene, Klinger invokes this to quantify Henry's status. When Henry knocks twice, Klinger says "Oh God, he's dead!"

* In the ''Series/MissionImpossible'' episode "The Town", a drugged and paralyzed Dan uses this to communicate with Rollin to let him know that his "doctor" is actually holding him prisoner. After the immediate danger is dealt with, they switch to blinking in Morse Code so that Dan can pass on more complex messages.
* One episode of ''Series/CriminalMinds'' featured a victim who was nearly paralyzed. When he tried to write, he only managed to scribble. Morgan has the nurses bring in a communication board so they can get a little more detail than "yes or no." It has the letters of the alphabet in a graph, so Morgan asks him to blink when he reaches the proper line then the proper letter to spell out his responses. He somehow confuses a tired, premature blink for an attempt to spell "Dani" instead of "Dana," despite the A coming before the I.
* ''Series/Peacemaker2022'': Peacemaker uses this to communicate with [[spoiler:the captured [[PuppeteerParasite Butterfly]] queen]]. [[TheDitz Vigilante]] doesn't seem to grasp that it has to be yes or no questions, although Peacemaker isn't much better, since he can only come up with questions based on the plots of alien invasion movies. They end up with no useful information by the end of it, [[spoiler:although it does play into Goff's HazyFeelTurn since she was grateful that Peacemaker showed her kindness.]]
* In ''Series/{{Taskmaster}}'' [[https://www.youtube.com/watch?v=bNoqOcA5apA contestants had to figure out what Alex was wearing in the other room.]] Alex had a horn to communicate and 4 out of the 5 contestants used once for yes, twice for no [[InvertedTrope while a fifth did it the opposite way.]]

** Meg volunteers to read to Mrs Deal, who never moves except to tap her finger. Meg wonders if she's trying to communicate. She tells her to tap once for yes and twice for no. Mrs Deal taps eight times. Meg concludes that she isn't really conscious and her finger is just twitching randomly. [[spoiler:It turns out she's trying to communicate by tapping in Morse code.]]

* ''Superior Court'': An episode of this 1980s courtroom drama had an episode where a witness, rendered a vegetable after a game of Russian roulette, testify at a murder trial by answering yes/no questions through blinking. His testimony helps convict the defendant of reckless use of a firearm. [[spoiler: The post-script is tragic: The young man dies shortly after the events of this episode.]]

* The early-90's UK kids' show ''Woof!'' has this when the main character becomes a dog.

* In ''Small Favour'', [[Literature/TheDresdenFiles Harry Dresden]] mocks this idea when his EvilDetectingDog seems unsure if something's wrong or not. "You know, Franchise/{{Lassie}} would have given a clear, concise message; one bark for [[ProfessionalKiller Gruffs,]] two for Nickelheads."

* A UsefulNotes/{{baseball}} example: In 2019, it was revealed that during the [[UsefulNotes/MLBTeams Houston Astros]]' World Series-winning season in 2017, they had used such a system as part of an elaborate scheme to use technology to steal their opponents' pitching signs, relayed between the pitcher and catcher. For background, it's legal for teams to try to decode opponents' signs; teams will try to do so when they get a runner to second base, giving him a direct view of the catcher. What's illegal is the use of added technology to do this in real time. The Astros used a video camera in the centerfield seats (also with a direct view of the catcher) to film the catcher's signs and sending the live video feed to a TV monitor directly behind the dugout, where players or team staffers decoded the signs. This trope was invoked when said players/staffers used various audio cues, most notably banging on a trash can with a baseball bat, to let Astros batters know what type of pitch was coming.

* ''LetsPlay/PiratesSMP'': Since Cruppy, a mysterious sea urchin-like creature which the cast finds on Day 1, doesn't speak, the pirates usually converse with it by telling it to jump once for yes and twice for no in response to their questions.

* During ''[[Literature/XWingSeries Wraith Squadron]]'', Gammorrean pilot Piggy's translator breaks, and his grunts aren't understandable, so when asking if he's okay, his squadronmates resort to this.

* In ''Series/Taskmaster'' [[https://www.youtube.com/watch?v=bNoqOcA5apA contestants had to figure out what Alex was wearing in the other room.]] Alex had a horn to communicate and 4 out of the 5 contestants used once for yes, twice for no [[InvertedTrope while a fifth did it the opposite way.]]

-> ''"Blink your eyes''
-> ''Once for yes''
-> ''Two for no..."''

--> Can you spin this gadget's blades one time for "no" and two times for "yes"?\\

* In ''Literature/RebornAsAVendingMachineINowWanderTheDungeon'' protagonist Boxxo [[ReincarnatedAsANonHumanoid has been reincarnated as a sapient vending machine]], who can only say a few [[WelcomeToCorneria canned phrases]]. He manages to still make friends with a young adventure called Lammis after she works out a system with him which she teaches others - for example he uses "Hello there!" to mean 'yes', and "Too bad!" to mean 'no', he also uses "You might win an extra item!" to alert Lammis of approaching enemies.

* In ''Literature/RebornAsAVendingMachineNowIWanderTheDungeon'' protagonist Boxxo [[ReincarnatedAsANonHumanoid has been reincarnated as a sapient vending machine]], who can only say a few [[WelcomeToCorneria canned phrases]]. He manages to still make friends with a young adventure called Lammis after she works out a system with him which she teaches others - for example he uses "Hello there!" to mean 'yes', and "Too bad!" to mean 'no', he also uses "You might win an extra item!" to alert Lammis of approaching enemies.

* In ''RebornAsAVendingMachineNowIWanderTheDungeon'' protagonist Boxxo [[ReincarnatedAsANonHumanoid has been reincarnated as a sapient vending machine]], who can only say a few [[WelcomeToCorneria canned phrases]]. He manages to still make friends with a young adventure called Lammis after she works out a system with him which she teaches others - for example he uses "Hello there!" to mean 'yes', and "Too bad!" to mean 'no', he also uses "You might win an extra item!" to alert Lammis of approaching enemies.
* {{Otaku}}: In his previous life Boxxo appears to be a fan of vending m

* In ''Literature/{{Worm}}'', in [[http://parahumans.wordpress.com/2012/08/25/snare-13-09/ Chapter 13.9,]] Skitter has a conversation this way with [[spoiler:Bonesaw]].