A Latin phrase meaning "The truth in the wine" (or, if you will, "In wine, [there is] truth"). Used in popular media to illustrate what happens when a character consumes alcohol and his true personality emerges. Truth in Television in that a drunk person has a much harder time keeping secrets and convincingly lying, but TV Land generally exaggerates it enormously. Symptoms include:
Loose Lips: A character gives away a secret that they would be adamant about not telling anyone, or would be careful to avoid even hinting at while sober; once drunk, they'll talk more easily, and tend to casually let the secret slip. The secret can be anything from a part of their personality that they keep repressed to a secret they're trying to guard for their employers(for example, the location of the MacGuffin).
Alcohol also causes her to undergo a more sombre personality inversion when Kaji is carrying her home. While we've seen hints of it earlier in the series, this the first moment where the alternating mask of confidence and professionalism/playfulness slips away completely and we are shown the full-extent of the fear and self-hatred that she carries inside.
Azumanga Daioh has strait-laced teacher Nyamo spending the weekend with the girls and drinking all the booze they smuggled in, to prevent Yukari from getting into it... and promptly telling the kids everything they ever wanted to know about sex (and probably almost certainly a few things they didn't).
Also earlier in the series, Nyamo and Yukari go to a restaurant. Yukari has too much to drink and undergoes a massive Personality Distillation.
In one Naruto Shippuuden omake, Shizune drunkenly confesses that she's jealous of Kurenai for having a boyfriend and maybe even husband while she is too busy working for Tsunade to find one. Unfortunately, Tsunade happens to hear it. (Ironically, this omake is shown a few episodes before Asuma dies and a couple months later in the manga Shizune herself dies. Temporarily).
Rock Lee turns from polite and formal into a cussing Boisterous Bruiser who can't tell friend from foe. Although recently, he's been able to recognize friends.
Another omake has a drunk Yamato complaining to Asuma that Kakashi's been dumping his responsibilities on him.
England from Axis Powers Hetalia considers himself a gentleman. He isn't quite one when sober, and he's often cranky and irritable. But when he gets drunk, he will run around naked and cackling, or sometimes start crying over that one ungrateful whelp. Sometimes both.
In To Love-Ru, it turns out that if you give the girls alcohol (or in this case, a pollen that makes them act drunk), they go through types 1 and 3 of this trope. Haruna's personality zigzags, Yui initiates Marshmallow Hell, Run tries very hard to kiss Rito but can never seem to get the right person, Mikan tries to confess, and Yami starts seeing things.
In a later flashback, Aion and Chrono enjoy a drink together. Aion compliments Chrono for his prowess on the battlefield, but Chrono shows regret for the lives that have been lost, leading them to start an argument over how they should treat the memory of their fallen comrades, with Chrono saying they should be honored and remembered and Aion saying that having pity for the dead is the arrogance of the living and "the dead don't care what you do."
In an audio drama that takes place after the cooking episode of Mai-HiME, the main characters (who are underage, as Nagi helpfully points out) start drinking alcohol, and end up confessing several personal details, such as Mai talking about having to look after Takumi after her parents' death.
In D.Gray-Man Komui even uses this for his own good. In the drama CD he feeds Allen, Lavi and Kanda a drug that should make them blurt out their true thoughts about his precious, precious Lenalee. It works. And aside of that has similar effects as alcohol. Complete with Alcohol Hic and Allen losing his temper. Allen - high on the drug - even mentions it feels just the same when he ate a box of liquor filled chocolates.
In one episode of Inuyasha the gang comes across some magic mist that makes people who breathe it get drunk. Sango, who's in love with Miroku but was in the Can't Spit It Out stage, suddenly becomes brazenly sexual and flirty ... with Inuyasha!
In a flashback arc of One Piece, mermaid queen Otohime gets so depressed about her subjects being afraid to integrate with the surface world that she gets rip-roaring drunk, takes up a microphone, and starts calling her people out on their cowardice.
In the Ace Attorney manga, Turnabout Gallows has Brock Johnson, who suspects Robin Wolfe killed his brother, giving alcohol to his brother Bobby Wolfe in order to get information, but Bobby apparently passes out after one beer without divulging anything useful. It turns out that Brock's real plan was to get Bobby drunk so that he could take the fall for him murdering Robin.
In Hanamaru Kindergarten, Tsuchida is only able to confess his feelings for fellow teacher Yamamoto when he's drunk. The other teachers are so happy that they start up a celebratory conga line-slash-bunny hop, singing "He confessed! He confessed!" Unfortunately, Yamamoto's drunk too, so she participates in the conga line too and then promptly forgets the whole thing upon sobering up.
Invoked by Fumi in the Aoi Hana manga, who uses the "liquid courage" of the Christmas champagne she'd been drinking to confess to Akira. Since she has already done so several times, and they are currently dating, an exasperated Akira can only exclaim "I already know that!"
Parodied in German comic Rudi. Some cute song birds start sieg-heiling, picking fights and generally acting like most obnoxious drunks after drinking beer.
In A Brief History of Equestria, it's shown that General Wind Whistler used this as part of her plan to build support against Commander Sullamander. She invited Generals Downpour and Torrent (who weren't blind supporters of Sullamander, like the other Joint Chiefs-Of-Staff) to her home for dinner, and slowly got them drunk on wine. Once their inhibitions were down, she got them to admit to hating Sullamander, and talked them into joining her in leading a coup. Wind Whistler's daughter, Pansy, bore witness to this and was extremely impressed.
A running gag in the Reading Rainbowverse is Fluttershy's passionate and outgoing nature... when drunk. She almost invariably regrets what she says because of how she says it... but never because it isn't true.
Naruto: "Ya know, I like this place. Earthland. Compared to mine, this place is peaceful. Sure there are fights but it ain't as bad as back home. There we always got a fight or a war to worry about. If it were up to me, I'd stay in Earthland."
Mirajane: "So why don't you?"
Naruto: "Because that crazy egomaniac Madara, wants to rule the world and that jerk who I promised to bring back are still running around."
In Frozen Hearts, this trope comes into play at the worst possible time. Heins, Hans' brother, who Can't Hold His Liquor, eats some fondue, gets drunk, and reveals his and Hans' true identities at Queen Elsa's masquerade ball, which they're attending with assumed names. This is something they desperately want to keep secret, since the truth getting out results in the brothers immediately being arrested and thrown in the dungeon.
When R!Syaoran starts drinking with Kurogane in Shatterheart, he reveals to be open with his emotions and very affectionate both things Syaoran is not when sober.
In the movie Blind Date, Kim Basinger's character undergoes a personality inversion from mousy and nervous to brash and wild after a few drinks. Hilarity Ensues.
Played with in Ratatouille, where an attempt to invoke this trope goes all too well, but not as intended. When Skinner gets Linguini drunk, trying to get him to confess he's being manipulated by a rat, he just gets an even-more-dorky Linguini (see: personality distillation in the description). Rat patootie, indeed.
In Eurotrip, the four main characters end up in a Czechoslovakian nightclub and all get smashed on Absinthe (green liquor that is very, very strong). Two of them, who happen to be twins, then promptly end up dancing together and making out....until they come to their senses mid-snogging session and scream their heads off.
Worst. Twins. EVER!
Charlie Chaplin's City Lights has the Tramp talking a drunken millionaire out of killing himself. The rich sot befriends him, invites him to stay in his mansion, drive his car, etc...but then turns on him when he sobers up. This cycle keeps repeating itself throughout the film.
In Happy Accidents, Sam keeps his identity as a time traveler secret from everyone but Ruby...until he gets drunk at an art show and promptly tells a small group of Ruby's friends.
"I distrust a man who says 'when'. If he's got to be careful not to drink too much, it's because he's not to be trusted when he does."
In State of the Union, Mary Matthews is told to refrain from speaking her mind for the sake of her husband's political campaign. Things don't turn out so blandly between her and the delegates after she decides to have what the Lady Drunk's having.
Shows up verbatim in Tombstone in a conversation between Doc Holliday and Johnny Ringo. Holliday insults Ringo and Earp says, "Don't mind him, he's drunk." This exchange ensues:
Doc: In vino veritas. ("In wine, truth." i.e. I mean what I say.) Ringo: Age quod agis. ("Do what you do." i.e. Watch what you say.) Doc: Credat Iudaeus Apella, non ego. ("Let Apella the Jew believe, not I." i.e. You're a fool to warn me.) Ringo: Iuventus stultorum magister. ("Youth is the teacher of fools." i.e. You're young and inexperienced, and that makes you the fool.) Doc: In pace requiescat. ("May he rest in peace." i.e. I'm about to kill you.)
In The Last Continent, the cowardly and cynical Rincewind turns into a boisterous optimist after a few Ecksian beers.
Carpe Jugulum has timid Non Action King Verence transforming into The Berserker after having a single sample of the Nac Mac Feegles' "brose," which is specifically designed to do just that. These are the fairies that consider Nanny Ogg's "sui-cider" a delicacy, after all. It's also lampshaded that giving him fifty times the brose, just because he's bigger, probably wasn't the best idea.
Downplayed in Unseen Academicals, where Lord Vetinari gets stone drunk. It's mentioned that men twice his size with a reputation for being able to hold their drink had been hauled home in wheelbarrows, but despite having drank just as much as they had the only noticeable difference in Vetinari's behavior is that he's a bit more sad, philosophical, and talkative than usual, and it's a bit harder the next day for him to do the crosswords in the morning paper. Apparently, he's very good at acting sober. Or very, very Knurd.
Played straight in that same book, where the normally strait-laced Glenda finally starts to loosen up after a few glasses of sherry.
A major plot point in The Three Musketeers hinges on a devastating autobiographical story Athos tells while drunk.
In Flowers for Algernon, the super-genius Charlie Gordon reverts back to a barely-functional moron (in the clinical sense) when he gets drunk.
In the second Montmorency book On the Rocks, the titular character gets addicted to opium and goes from secretive, but fun, to broody and possibly too loose-tongued for the safety of himself and others. Or so Fox-Selwyn tells us; Montmorency doesn't spend much time actually on opium, most of the time he's having withdrawals.
Ovid advises men to fake this in a chapter of his Ars Amatoria. Depending on interpretation, he either says that women will believe drunk men to tell the truth about sweet and true love, or that men will get away saying really dirty things to respectable women, since the woman won't mind and the men watching over the woman (father/brother/husband etc.) will assume the "advancer" is just blubbering drunk nonsense.
Alluded to in The Serpent's Shadow, when Maya Witherspoon brings a young man injured on the orders of one of the book's villains to the Fleet Street Clinic. The head nurse is worried about the attraction he shows to a female medical student/clinic volunteer, until Maya points out that there's just as much truth in a quarter-grain of morphine as there is in wine.
Wine is routinely used as a quick and dirty version of Truth Serum in A Song of Ice and Fire books. It's quite effective, especially on prisoners who probably aren't eating too well.
Although it is very subtle, in Sansa's last chapter for A Feast For Crows, Littlefinger is clearly drunk on wine and hubris, and is a lot more open in his desires to kiss Sansa and reveal his plans to her.
In "The Evil Drink Does," from Isaac Asimov's Azazel, the main character suggested that a rather straitlaced woman, who was worried about being a perpetual virgin, should loosen up a bit by getting drunk, only to be told that a single drink made her violently ill. He then asked the title imp to adjust her body chemistry so that alcohol became a "healthful food" for her. That resulted in her becoming thoroughly uninhibited. Unfortunately, due to its having actual nutritive value and to the quantity she drank for years afterwards, she also became morbidly obese.
Live Action Television
In Smallville, while Clark is immune to alchohol, red kryptonite is his personal replacement, explicitly stated to strip away his inhibitions. So far, while on red kryptonite, he has managed to buy expensive stuff with money stolen from his parents, make advances towards Lana, Chloe, Lois, Alicia, and other girls, run away to Metropolis, "married" Alicia, crash Lana's engagement party and dropped cruel (but arguably accurate) comments to Martha and Chloe, and become best pals with Zod.
In Breaking Bad season 4, after Walter drinks too much wine, he hints to Hank that Gale was not the mastermind behind Blue Sky. In other words, Walt sheds away his cold, logical exterior, and gives us a sneak preview of his egocentric reasons for getting into the business in the first place.
Played for Drama on an episode of Community titled "Mixology Certification", which is centered around the group's visit to the bar to celebrate Troy's birthday. Almost everybody gets drunk, leading to minor personality changes and lost inhibitions (including Jeff and Britta almost blowing up their secret Friends with Benefits arrangement). The celebration ends with all the characters miserable and disillusioned.
Subverted in one episode, where House pretends to do this to break up Cuddy and Lucas
In another episode, Thirteen says, "Being drunk doesn't change who you are, it just reveals it."
An episode of Lexx, when they met Oberon and Puck and Oberon's Wife (Titania?). Titania was played by a bearded dwarf in drag and Oberon seems to really hate being married to "her". Stanley asks Puck how they got together in the first place, it's explained that Oberon was very very drunk. Puck invokes the trope when Stanley is doubtful as to how drunk one would have to get to find Titania attractive: "So yer saying, he's the kind of guy who really prefers..." (cut off by Puck before he can explicitly question the Fairy King's heterosexuality)
Oberon actually tries to marry Stanley later in that same episode, ostensibly as an upgrade from his even more mannish current wife, but given what Puck has told us...
Parks and Recreation really had fun with this in "The Fight". There was super-positive Leslie crying and babbling over her fight with Ann, Tom's inflated ego, serious Ben saying "Baba Booey" in an extremely self-satisfied tone, Andy's intense singing, April's incoherent rapid-fire Spanish, and... this◊.
This is why Elaine in Seinfeld can't keep a secret.
Elaine: Come on, tell me! I'll put it in the vault! Jerry: No, the vault's no good. Elaine: Why's the vault no good? Jerry: Because everyone knows the combination. [gestures drinking from a bottle of liquor]
A science fiction version occurs in Star Trek: The Next Generation episode "The Naked Now", which includes Wesley taking over the ship, Tasha Yar seducing Data, and Picard and Crusher almost admitting their love for each other. The classic Trek version was better, with Sulu rampaging shirtless through the ship with a rapier.
O'Brien: You're not an in-between kind of guy. People either love you or hate you. Bashir Really? O'Brien: I mean, I hated you when we first met. Bashir: I remember. O'Brien: And now... Bashir: And now? O'Brien: Well... Now, I don't. Bashir: That means a lot to me, chief, it really does. O'Brien: And that is from the heart! I really do... not hate you anymore.
Barney goes through several stages of drunkeness, including "Richard Dawson Drunk" (he kisses every woman he meets like the Family Feud host); "Friends With Strangers Drunk"; "Marcel Marceau Drunk" (he walks like the famous mime's walk-against-the-wind routine); "Jabba Drunk" (he talks incoherently like Jabba the Hut; and finally, "Truth Serum Drunk", where he compulsively tells the truth.
"Thank you summer barbecues, for always featuring fun family games like horseshoes, croquet, and 'Let's see how many daiquiris Grandma can drink before she gets racist'."
A recurring character on Saturday Night Live, during the Weekend Update segment, is Drunk Uncle. His coversations always devolve into rambling rants about all the problems he perceives in modern culture.
"I remember the days when the television industry was run by giants. Whereas now it is run...BY PYGMIES! LIKE HIM! AND HIM!"
Double-subverted on Doc Martin. Louisa tries this on Martin, but he says that alcohol just makes him sleepy. But then he admits that he loves Louisa. And then he falls asleep.
In Dorothy of Oz, Mara Shin blurts out to Abee about her huge crush on him...all the while yelling at him that he can't be the real Abee because her Abee is a kind and gentle person. Abee is understandably confused, especially when she compares him to both a fish cake and a gourmet pastry.
Abee: Should I be flattered or angry?
Exemplified in the country song "The More I Drink". In fact you find this trope a lot in country music.
Doctor Jimmy and mister Jim When I'm pilled you don't notice him, He only comes out when I drink my gin.
The David Burns song "The Whiskey Never Lies" is all about this trope.
You said you had it bad fer me, you'd take me to the moon You said no other moved you so, no other made you swoon But when the drink was in your blood you sang another tune And that was when I learned the truth, the whiskey never lies
The Lonestar song Tequila Talkin' is about the aftermath of this. The singer spends the entire song trying to convince his ex-girlfriend (and quite possibly himself) that the only reason he told her that he still loved her and wanted her back was because he was drunk.
It was just the tequila talking When I told you I'm still not over you I get a little sentimental When I've had one or two And that tear in my eye was the salt and the lime Not the memory of you walking If I said I'm still in love with you It was just the tequila talking
They Might Be Giants' "Your Racist Friend" touches on this in passing:
He let the contents of the bottle do the thinking Can't shake the devil's hand and say you're only kidding
The whole plot of Bertolt Brecht's play Mr Puntila and His Man Matti is an illustration of this trope. Puntila, when sober, is a boorish, exploitative boss, but get him drunk and he becomes the most affable and generous of men.
This trope plays a major role in the play God of Carnage, as well as its film adaptation. It plays out mainly in the Personality Inversion variety.
The heroine of A Dance with Rogues is way, way more promiscuous when really drunk. The two times the player has the option of getting really drunk are during the scene with Pia in the first chapter and the contest with Gemli in the second; during the first if you get drunk enough you don't remember what happens but Pia implies it was really, really great, during the second if you lose the drinking contest your character, a human with relatively normal sexual tastes, will screw a filthy, stinky, hairy, dwarf.
In the first season of TellTale'sSam & Max games, during the fourth episode, Bosco will hawk a "truth serum" that, upon purchase, turns out to be a bottle of vodka. This seems less useful than Bosco makes it out to be, since the duo is well aware that In Vino Veritas is under no circumstances guaranteed, but they do in fact use it as such when Max needs to start a war and Whizzer is being tight-lipped to maintain peace among the brothers.
How they managed to get drunk off non-alcoholic beer... well, it's probably the Placebo Effect.
Slightly subverted in the case of Detective Adachi, who lets a few things regarding the case slip while drunk at the Dojimas', but no more than he usually does sober. Also averted, as he manages to not reveal his true intentions and crimes even while drunk. His ramblings while drunk may, in fact, also be the result of him being just as duplicitous as he usually is, making this a complete aversion. Hard to tell.
One quest in Jade Empire has you getting a man named Three SheetsDutong drunk to confess that the Imperial writ that he used to cheat Old Mother Kwan out of her tea house is fake. There are three stages of drunkenness; first he's cheerful and doesn't want to talk about something as "dry and boring" as the writ, then he's depressed and is willing to confess to faking the writ, then he gets too paranoid and must be given a sobering potion. The player must give him the right number of drinks to get him into the second stage of drunkenness to finish the quest.
In Dragon Age II, we have Fenris. It is shown during a few of his more personal cutscenes between him and Hawke that he can really hit the bottle. In one scene alone there are at least two empty bottles on the table he and Hawke are sitting at and he is working on a third. Hilarity Ensues when he tells Hawke (if Hawke is a mage) that he or she is "A finer mage I've never met" which goes completely against his Mage hating usual self. He also throws a few rather sexy smiles Hawke's way, further showing how much of his usual broodiness goes away when he drinks. In Vino Veritas indeed.
Brought up by an NPC in Radiant Historia when he mentions how alcohol sales are high in times of war.
In Hanako's route in Katawa Shoujo, when they drink wine at her party, she gets drunk and starts clinging at Hisao, telling him she doesn't want him to leave, altogether being much more open about her emotions than usual. Hisao, who had also been drinking, finds this quite discomforting and is very firm about putting her to bed before either of them do anything they'd regret.
TheDemoman from Team Fortress 2 is actually a genial, easy to get along with guy off the clock and off the bottle. On the job, and with ample swigs of Scrumpy, he becomes the Demoman everyone is more familiar with.
In Jagged Alliance 2, one of the first missions the player gets is to organise food shipments to the besieged rebel base. The only person who is capable of doing so is Father Walker, a priest sympathetic to the rebel cause, but he initially refuses to help out of fear. However, he is also a well-known drinker and once you give him some alcohol, he drunkingly agrees to supply the rebels with the much-needed food.
In It's Walky!, Jerkass Mike becomes sweet and friendly after a few drinks. His girlfriend, Dina, quickly takes advantage of this and attempts to keep him perpetually drunk. Note that this is basically treated as rape (though the rest of the cast doesn't care because its Mike and they have their own problems), but when he finally sobers up he comes within an inch of killing Dina.
And it's back in Shortpacked!, with Amber (although she just blackmails him so she can date him sober).
Also, Helen tends to blurt out things she really shouldn't after she's had a few too many spiked popcicles.
Jack's girlfriend, the devoutly Christian Katy-Ann, seeks to understand his drinking by getting drunk herself for the first time, and reveals to her friends her repressed sexual urges for him. The scene is mainly Played for Drama, but culminates in a Played for Laughs moment where she calls out for Jack (who isn't there) to ravish her as she begins to strip.
Bun-Bun the Killer Rabbit from Sluggy Freelance is usually a knife-wielding psychopath with a hair-trigger temper... but give him enough to drink, and he becomes a genuinely nice and friendly fellow. His drink of choice is Rum. Which may have something to do with his past(s) as the captain (and first mate) of a shipful of the Pirates above the Oceans Unmoving...
The cast once shot him with a tranquilizer dart. He got really happy and friendly (like the human who'd just gotten tranqs too), and very joyfully beat them all up.
PeeJee: Sounds like someone's cranky because he can't even maintain his virtual romances. Davan: At least with computer games there's a cheat code. I'd have killed for a button combination to enter that forced the women I've seen to say what they actually mean. PeeJee: Most guys I've dated have found that "up, down, circle, circle, three shots of vodka" works well.
In thisQuestionable Content strip, Marten says some unkind things to Faye while drowning his sorrows over Dora breaking up with him because she needs to work out her own trust and intimacy issues. Of course, it has far more to do with his current emotional state than his true thoughts about Faye and his relationship with her. A better example might be his earlier drunken conversation with Angus in regards to Faye (in which he candidly disclosed their history and his assessment of whether Faye could handle a real relationship).
Eerie Cuties had an all-girls party where a very young succubus drank some liquor and proclaimed "I feel like alllllll my inhibitions just melllllted away". Oh, and aside of girls being uncomfortable with her sudden urge to cuddle up in the absense of boys, they almost have seen her soul-draining a small crowd by accident once — those guys were reanimated, but the aftermath didn't look pretty.
Both Rebecca and Donnie from Demo Reel share too much about their pasts when they're high for the former and drunk for the latter.
The Tom and Jerry cartoon "Part Time Pal" has Tom getting all chummy with Jerry after taking alcohol.
Columbia's "Pickled Puss", released a year later (1948), used that same plotline. A cat becomes friendly with a mouse he'd been chasing—to the point of annoying him—after eating several herring pickled in pure hootch.
In a variation, Terrytoons' Little Roquefort cartoon "Playful Puss" has Percy friends with Roquefort while under the influence of catnip.
Jared from Superjail! is a neurotic, spineless wreck of a person normally, so you can imagine that he's given into vice before. It's just that as a recovering alcoholic, even being near alcohol makes him hallucinate violently.
Metalocalypse: Every single of the band's mothers, but especially Toki's, who goes from an incredibly strait-laced religious person with a high amount of restraint to a total pervert when she gets drunk on alcohol.
And let's not forget the band's manager/lawyer Charles Ofdensen, who is generally a soft-spoken, sort of uptight guy...until you pour enough alcohol into him. Then, he starts doing things like playing with Nathan Explosion's hair.
On Daria, Trent suggests that he and Jane get through a family reunion by passing out drunk. Jane points out that not only is she underage, but Trent tends to get "honest" when he's drunk and it's probably not a good idea for them to tell their relatives what they really think of them.
Subverted in Wonder Woman. Steve Trevor buys rounds of tequila shots for him and Diana in an attempt to get her to loosen up and open up to him. Unfortunately for Steve, Amazons have an incredibly high tolerance to alcohol, so after quite a few shots, Diana is still completely sober while Steve can barely sit up.
"Crumley Cogwheel" was a 1963 Paramount Modern Madcap about an office schlub who has spent 20 years with Michigan Nuts And Bolts and had never asked for a raise. His boss gives him a week to do so or else he will be fired. On the last day, Cogwheel is on his lunch break, and instead of going to his usual tea house, he goes into a bar. Only after he gets plastered does he summon up the courage to not only barge into his boss' office during a board meeting, but also demand a raise. His boss is completely impressed, and gives Cogwheel his raise—of one dollar. Stunned of utter disappointment, Cogwheel faints (Boss: "Poor guy...I guess the shock was too much for him").
The Beatles episode "I'm Down" has the boys helping an Italian wine-making family replenish their inventory. Wine is consumed, but nobody shows any sign of being drunk.
Real Life example that may or may not be true. This is the reasoning behind a custom attributed to the Germans and Persians by Tacitus and Herodotus respectively: In their assemblies, matters are debated twice. Once sober, once drunk. Though it's more a 'too drunk to think their way through lies and subterfuge' than personality shifting.
The Romans didn't trust completely sober people, as they thought you could never be certain of what such man was thinking or plotting, if he never allowed wine to loosen his tongue.
Caesar was known for never drinking or indulging in vices of any kind, always telling the truth and his general incorruptibility. This really annoyed his rivals.
From the mouth of John Wayne, "I never trust a man that doesn't drink." Probably for the same reason as the Romans.
Real Life aversion: King Charles II of England said of Prince George of Denmark (Queen Anne's husband), 'I have tried him drunk, and I have tried him sober, but there is nothing in him.' Boring guy all 'round.
Queen's song "The Show Must Go On," widely considered to be one of Freddie Mercury's best performances, was recorded while Mercury was severely ill and close to death due to AIDS (the song was released a month before his death). It was originally thought that due to his illness, Mercury wouldn't be able to sing the song, but he took a swig of vodka and proceeded to nail the song. In one take.
Several of Mel Gibson's rants have been attributed, correctly or not, to his self-admitted problems with alchohol.
The basic concept behind most real life Truth Serums is that they render a person more likely to talk in general and less able to come up with a convincing lie. Incidentally, the only two substances that have been proven to be fairly consistently effective as (relative) Truth Serums are alcohol and marijuana. The former was a favorite of the KGB, whose agents were able to keep cover while their Western opposite numbers started gushing. The latter was tried out by the FBI, in the form of THC-laced cigarettes, on a member of The Mafia, who spilled the beans on a heist, embarrassing the CIA's MKULTRA (which was trying to do the same thing with more exotic substances like acid) in the process.
The 'Tokubetsu Kogeki'('Kamikaze') pilots were given a mug of sake as part of their pre-mission sending-off ceremony. Symbolic value (minimal) aside, it was most likely included to dampen their nerves and fear. This was common practice in many branches of all armed forces participating in the conflict, air and naval forces (wherein losses were radically fewer in absolute and usually in relative terms) aside.
Vodka was the most important alcohol of the war, present as it would have been (at least in part, as per the 'let's all share a bottle between our squad before we assault that machine-gun nest/attack that panzer with our last molotov cocktail/use sharpened shovels to charge and clear that house of Germans' mentality) in most if not all the corpses of the 8-11 million Soviet soldiers who died in the defence of their Motherland.