[[quoteright:300:[[Webcomic/SchlockMercenary http://static.tvtropes.org/pmwiki/pub/images/OnThree_5797.png]]]]

->'''Chandler:''' Okay, on three. One... Two...\\
'''Joey:''' Why don't we just go on two?\\
'''Chandler:''' Why two?\\
'''Joey:''' Because it's faster.\\
'''Chandler:''' Yeah, I coulda counted to three like four times without all this "two" talk.
-->-- ''Series/{{Friends}}'', when the gang is lifting a heavy entertainment center into place.

Any time precise timing is called for, you're likely to hear the phrase "On three: One, two, THREE!"

Since this has been heard countless times before, variations are common. A common parody is: "WAIT! Do we go on three, or do we say 'One, two, three' and then go?" This usually results in an awkward conversation about how best to count or the characters becoming even more confused and going at the wrong time or missing their opportunity entirely. (GenreSavvy characters may avoid this by counting down from three instead: "Three, two, one, GO!") Another common joke is to have someone simply go "Three" without counting to one or two first.

If the action which the count builds up to is a ''painful'' one (e.g. ripping duct tape off a bound captive's mouth), then the action may be taken ''before'' reaching the promised "three", to get it over and done with before the subject of said action realizes it's started.

[[JustifiedTrope The reason why "three" is the usual number]] is because it's the smallest number of points you can use to establish a regular time interval. If you only count to one, nobody can react fast enough to the person saying "one". If you only count to two, you don't know how long the time is supposed to be between numbers, so nobody knows when to listen for the "two" either. Counting to three establishes both the point in time and interval between numbers, so everyone can figure out when the "three" will happen.

SubTrope of RuleOfThree. Not to be confused with CountingToThree, which is when you don't ''want'' the person counting to get to three, or with OneTwoThreeFourGo (in which the "go" is the Japanese word for "five").



* The dub of ''Anime/YuGiOh'' has Joey and Tristan agree to try ramming a blocked door "on three", then proceed to shout "Three!" in unison immediately to ram right away. And then they shout and shove again and again until the door breaks. Well, their best friend is dying in a fire in there, what do you expect?
** This goes on to become their RunningGag.
* Similarly, in the ''Anime/RebuildOfEvangelion'' English dub:
-->'''Misato''': "Push on three... THREE!"

[[folder:Fan Works]]
* ''FanFic/PaperMarioX 2'':
-->'''{{Franchise/Sonic|TheHedgehog}}''': ''[to [[Franchise/TheLegendOfZelda Link]]]'' Okay, you're going to count to three. When you say "Two", you open the door!\\
'''Link''': Why two?\\
'''Sonic''': You'll see…

* ''Film/LethalWeapon'' makes a running gag out of this joke.
* Averted in ''Film/RobinHoodMenInTights'' with "On the count of 'Kick'!"
** Later it was "On the count of 'Jump'! Wait for it..."
* A running gag in ''Film/MontyPythonAndTheHolyGrail'' was that King Arthur couldn't say the word "three", substituting "five" for it until corrected by one of his subordinates. When it comes time to toss the HolyHandGrenade, he miscounts again-fortunately the grenade didn't go off until it was thrown next to the desired target.
* ''WesternAnimation/YellowSubmarine'', as Music/TheBeatles are about to sing ''Sgt Pepper's Lonely Hearts Club Band''.
-->'''John:''' Okay, on the beat...A-one, a-two, a-three, a-four, a-five, a-six...
-->'''Ringo:''' Hey! Can't you make it three?
-->'''John:''' Oh, alright! On the beat...A-one, a-two, a-three...
* In ''Film/MadMaxBeyondThunderdome'', Max has to yank an arrow out of another character's leg, says they'll do it on the count of three, and of course does it on one.
-->'''Pigkiller:''' ...what happened to two?
* Shows up near the end of ''Film/SisterAct'', when [[TheFamilyForTheWholeFamily Vince's goons]] are getting ready to off Deloris:
-->'''Joey:''' Okay, we go one, two, three, shoot.
-->'''Willy:''' Wait. We don't go one, two, and shoot on three?
-->'''Joey:''' Get over there!
* ''Film/SnowWhiteAndTheHuntsman''. Although no counting to three is involved, there's an amusing scene when the dwarves are sneaking into the castle through the sewer system.
-->"We move as one. ''(try to move, then realise there's not enough room)'' After you."
* ''Film/XMenApocalypse'': Nightcrawler messes up the countdown for Cyclops to use his powers because the former gets distracted when he realizes that he only has two fingers (not counting his thumb).
* ''WesternAnimation/TheLEGOMovie''; the robot cowboys trying to catch Emmet, Wyldstyle, and Vitruvius plant some dynamite outside their room:
-->"On three. One!" ([[StuffBlowingUp Boom!]])
* Subverted (and very sensibly) in ''I Survived A Zombie Holocaust'', when Wesley's hand is bitten and Susan needs to [[LifeOrLimbDecision chop it off]] to stop the infection. He sets his wrist on the chopping block, but barely has time to ''start'' suggesting a count of three before she brings the ax down, not allowing him time to flinch or chicken out.
* ''Film/Scarface1983''. The gangland soldiers about to kick down Tony Montana's door can be seen doing a silent version, right before Tony's "[[BfG little friend]]" blows open the door in their faces.

* Played with in ''[[Literature/{{Newsflesh}} Feed]]''. George and Shaun agree to activate their mandatory zombie-infection blood tests on three, as loss of speech function is an additional warning sign of infection. [[spoiler:But they have a prior standing agreement to actually go on ''two'', as loss of memory is also a warning sign.]]

[[folder:Live Action TV]]
* ''Series/ThatMitchellAndWebbLook'' in a sketch about a hostage negotiator.
* ''Series/{{Friends}}'': The cast attempts to move a heavy piece of furniture and Joey asks why it has to be a count of three instead of two.
* In ''Series/AllInTheFamily'', Gloria and Mike are fighting; Mike locks himself in the bathroom. Gloria says she's going to break the door open "on three". Mike opens the door as she says three (because he assumed it was "one, two, three, then hit")--and Gloria slams into him (she started running at "two" to hit on "three").
** A similar thing happens in an episode of ''Series/DrakeAndJosh''.
* Played with in ''Series/HerculesTheLegendaryJourneys''. Herc and Iolas agree to jump on three......then say three and jump.
* Played with in the ''Series/{{Supernatural}}'' episode "I Know What You Did Last Summer", when Sam is resetting Dean's dislocated shoulder:
-->'''Sam:''' Okay, on three. One,
-->'''Dean:''' AUGH!
* ''Series/{{Mash}}'': In "There Is Nothing Like A Nurse," the nurses are vacated due to an impending enemy attack. Frank manages to telephone Hot Lips, and like schoolkids, they say to count three before hanging up. Only Hawkeye and Trapper, who have been eavesdropping, finish it.
* ''Series/TheBigBangTheory'': When Howard, Raj, and Sheldon have a "last one touching the ring wins" contest and nature calls:
-->'''Raj:''' On the count of three. One, two...
-->'''Sheldon:''' Wait! Just to clarify, when you get to three, do we stand up, or do we pee?
* Harry Kim introduces newly de-assimilated Seven Of Nine to this in ''Series/StarTrekVoyager''. Her response: "[[BoringButPractical Crude, but effective.]]"
* In ''Series/{{Life}}'', Detectives Crews and Reese want to arrest a coke-dealer in an ice-cream truck (who has an armed partner hiding behind the counter):
--> '''Crews''': ... but I'm going to count to three and then *I* plan on shooting [''the partner'']. One... two... [''fade to commercial and'' '''BANG''']\\
[''after break'']\\
'''2nd Perp''' [''on gurney'']: You didn't say "three"! You didn't even ''get'' to three! You shot me on ''two''! You didn't get to three....\\
'''Reese''': He's right, you know — you didn't get to three.\\
'''Crews''': I rounded up.
* Combined with TwoScenesOneDialogue in ''Series/PersonOfInterest''. In "If-Then-Else", Martine and a squad of Samaritan agents are getting ready to burst into a room to kill Team Machine, who are about to escape through another door to the elevator room.
-->'''Martine:''' Shots to the head and center mass. On my mark, one--
-->'''Reese:''' ''(peering through door window)'' --two, three!
* ''Series/AgentCarter''. Edwin Jarvis and Peggy Carter are cuffed to the desk in an interrogation room, so decide to use it to break the glass. Jarvis keeps interrupting to ask questions, but as per the RuleOfThree they succeed on the third try.

* The studio version of ''Music/ElectricLightOrchestra'''s ''Four Little Diamonds'' starts with "After four. FOUR!", then the music immediately begins.

[[folder:Video Games]]
* ''VideoGame/{{Portal 2}}'' has Wheatley disengaging himself from his management rail "on three", only to chicken out thinking Chell won't grab him (he thinks she's brain damaged, after all) and back up. Then he decides to let go on "one" so as not to psyche himself out.
-->'''Wheatley''': Get ready to catch me, alright? On the off-chance that I'm ''not'' dead the moment I pop off this thing. On three. Ready? One. Two. THREE -- that's high, it's too high, isn't it, really. Okay, going on three just gives you way too much time to think about it. Let's... go on one this time, okay ready?

[[folder:Web Comics]]
* In ''Webcomic/{{Vexxarr}}'', the Plant AI's in their HumongousMecha had formed a line to [[http://www.vexxarr.com/archive.php?seldate=041309 execute the engineers "on three"]]. Luckily, Vexxarr had previously stolen one of those HumongousMecha.
-->'''Plant AI:''' Ok then, ready your aim. One... Two...
-->'''Vexxarr:''' [[BondOneLiner ...three]].

[[folder:Western Animation]]
* Used by 625 in ''WesternAnimation/LiloAndStitchTheSeries'' to avoid work.
* The WesternAnimation/ExtremeGhostbusters came up with a solution to the "Should we go on two or three?" dilemaa; their BattleCry was "OnThree! '''THREE'''!"
* WesternAnimation/DangerMouse: In ''The Good, The Bad And The Motionless,'' DM realizes that whatever he says controls what happens (as he's at Stonehenge and his evil alter ego is manipulating things). As he's confronted by three blue demons and flanked by his evil self:
-->'''DM:''' Demons, you're just a figment of his imagination, so after three, vanish. Three. (''the demons vanish'')