Undercover As Lovers

"Mal: Whatever happens, remember that I love you.

Zoe: Sir?

Mal: Because you're my wife.

Zoe: Right, sir. Honey."

- Firefly, "The Train Job"

Alice and Bob need a disguise. Maybe they're detectives, maybe they're spies, or maybe they're just on the run from the law. For whatever reason, the disguise they decide to adopt requires that they pretend to be a couple. Hilarity Ensues!

This may be a sign of Unresolved Sexual Tension between them; alternately, it can be used to highlight the lack of tension, by showing just how unnatural it feels to have them play the role. Either way, expect a huge amount of bickering and an agreement not to use tongues.

Compare the rather briefer Fake-Out Make-Out, which may become necessary at some points.

See also Smithical Marriage, The Beard.

Anime and Manga

 * In Full Metal Panic, do this while they gather information for Tessa in Russia. There were definitely deeper feelings on  part, though  is harder to read.
 * An flashback arc in the Rurouni Kenshin manga, and the anime's prequel OVA, revolves around Kenshin in his assassin days posing with Tomoe as a married couple to avoid Shinesengumi detection. It grows into real love just in time for things to end poorly.
 * Hei and Yin from Darker Than Black pose as newlyweds in order to hide out at a resort while on the run in the Gaiden OVA.
 * Trigun: Millie Thompson and Nicolas Wolfwood perform this, but in a twist it's not to protect themselves; it's to hide an escaping slave by hiding her under Millie's dress, with her posing as a pregnant woman. Millie and Nicolas then stroll along, pretending to be a happy expecting couple as the slave's pursuers pass them by.
 * Aversion In Pokémon: Upon learning that James was an heir to a large fortune and could come upon that inheritance just by marrying, Jessie initially suggests that she and James falsify a wedding to each other in order to steal the inheritance.

Comics

 * During the Civil War story line, Sue and Johnny Storm had to pose as Lovers. Being siblings, this obviously was extremely Squicky for them.

Film

 * James Bond examples:
 * Casino Royale
 * The Spy Who Loved Me - James and Major Amasova, while visiting Stromberg.
 * The first Austin Powers movie did this, complete with clueless Austin using the inappropriate pseudonyms Richie Cunningham and Oprah.
 * The Fourth Protocol. The KGB agent played by Pierce Brosnan picks up his 'wife' (actually a female military scientist) from the airport, and suggests they share the bed as per their cover story (he's been getting rather frustrated thanks to a flirtatious neighbour). She tells him to get lost, but they end up sleeping together anyway after a sweaty session
 * Lois and Clark in Superman II. They pose as a honeymooning couple to expose a corrupt hotelier.

Literature

 * In the Oathbound series by Mercedes Lackey, Kethry and Tarma pretend to be lovers on a few occasions. They're actually Heterosexual Life Partners, but there's enough Les Yay between them that they pull it off.
 * Talia and Kris did the same to fool possible spies during their diplomatic mission to Hardorn in Arrow's Fall. Having once had a just-friends sexual relationship, they were able to be very convincing about it.
 * In Single & Single by John Le Carré, Oliver Single and his bodyguard/minder Aggie travel to Berne using his alias Hawthorne, with Aggie using the name of his ex-wife. When they believe they've been spotted by the bad guys, the switch to another pair of pre-arrainged identities--a married couple again--before making an unscheduled and unauthorized escape to Istanbul.
 * Perry Mason and Della Street disguise as a couple with a baby in the Case of the Deadly Toy, to hire a babysitter they need to question.
 * In Dresden Files, that's how Red Court Vampires frequently operate. Pretending to be a married couple makes it easier to deal with law enforcement agencies, your actions are considered less suspicious and people generally trust you more.
 * In the Sword of Truth series, Jennsen and Sebastian use this technique while at the People's Palace. Jennsen seems to be fine with Sebastian's suggestions, until he decides that she should pretend to be pregnant, as well.
 * Dusty Fog and Belle Boyd pose as husband and wife in The South Will Rise Again by J. T. Edson.
 * When Rogue Squadron infiltrated Imperial Center in various disguises, some of them posed as lovers, most notably Corran and Erisi.
 * In Honor Harrington Victor and Ginny use this as a cover on multiple occasions.

Live Action TV
"Cavanaugh: I'm good at destroying things. Caffrey: That's why I married you. (both smile)"
 * The Avengers TV series does it in Death on the Rocks where Steed and Cathy Gale must pretend to be husband and wife--probably the UrExample since it was from 1962 and there just aren't many series prior to that where the woman had enough of an active role to get an undercover mission (and to have UST, since that implies that her main role in the series isn't already to be a love interest).
 * Aside from the quoted mention on Firefly, Jayne and Mal pretend to be husband and wife in one episode. Hilarity ensues:
 * NCIS, "Under Covers": Tony and Ziva pose as a husband and wife team of assassins and fake having sex more times than is really necessary to maintain their cover.
 * Not to mention the act is apparently so convincing they fool the FBI agents who are secretly monitoring them, who insist, even after being told repeatedly that the entire situation was an act, that they can't be fooled and it was real.
 * Five seasons later, it's implied that the sex was real.
 * Happened on The Bill at least once.
 * On the second season of Supernatural, Jo poses as Dean's girlfriend in order for them to investigate an appartment where various girls had gone missing.
 * There is also an episode in Season 3 in which Dean and Bela pretend to be a couple at a social event in order to steal a Hand of Glory from the place.
 * Averted on New Tricks, when Brian is paired up with a young and beautiful professional undercover cop. He explains the situation very cautiously to his wife - only to be discomfited when she bursts out laughing.
 * Happened on Bones, in an episode where Booth and Brennan go undercover as married circus performers.
 * And there's the episode where they go to Las Vegas and pose as a "loosely committed" couple. (Read: Brennan nixed the idea of marriage because she doesn't believe in it)
 * Season 5 has an episode where they go semi-undercover to Bones' high school reunion, with Booth posing as her husband. Made a thousand times more akward by the fact that
 * One episode has Angela and Sweets going undercover as a couple to nab possible murder weapons.
 * Veronica Mars did this to Logan at the Neptune Grand once to look for his mother.
 * Life On Mars. Sam Tyler and WPC Cartwright pose as a married couple to investigate a wife-swapping group. Interestingly the most UST comes not from this situation, but in the scene where they're making up a Meet Cute cover story.
 * The X Files ("Arcadia"). Mulder and Scully pose as a married couple while investigating a Planned Community With A Dark Secret. Given their Celibate Hero nature, it was more an opportunity for snarking at each other than UST. Such as Mulder claiming they met at a UFO conference. "She's into all that New Age stuff. I don't know why she falls for it." Scully somehow manages to give a shamefaced smile through gritted teeth.
 * But everyone knows Mulder was lucky to escape that assignment with his life. Or other important parts...
 * The Hilarious in Hindsight aspect about that episode is that it wasn't originally classified as an X-File. It was simply a missing persons case in a creepy town. Which means that whoever was running the case though that out of all the male/female patnerships in the FBI qualified for the case, Mulder and Scully would be most believable as a married couple.
 * La Femme Nikita. Nikita and Michael did this on several occasions. In one episode they're flat out told by their controller that they're to have sex.
 * Lois and Clark in Lois and Clark, again posing as a honeymooning couple. This time it was to spy on the bad guys across the street from the hotel.
 * Threshold. In order to investigate a small town called Allenville, Caffrey and Cavanaugh pose as newlyweds looking for a home. Far from being uncomfortable with this, they actually joke about themselves as a married couple throughout the episode.


 * In Babylon 5, during the EA Civil War arc, Marcus and Franklin adopt false IDs to sneak into Mars. The Resistance's access to fake IDs is "limited to what [they] can steal", so they end up taking the IDs of newlyweds: Jim Fennerman and Daniel Lane, on Mars for their honeymoon. Not especially sensical, but very funny. Also noteworthy for the fact that no one (even Marcus and Franklin, after the initial "WHAT!?" reaction) finds it unusual. (Would that be Fortunate Implications?)
 * Probably Confirmed as an example of J. Michael Straczynski incorporating the normalcy of homosexual relationships in the futuristic world of the show in a way that both does not come off as Anvilicious and is easily overlooked by the censors, since he pulled a similar feat earlier with the Ivanova-Talia relationship.
 * In Knight Rider 2008, Mike and Zoe pose as a honeymooning couple in the course of an investigation in a Mexican resort.
 * This happens over and over in Chuck, usually when they attend parties that the big baddie is throwing. In one episode this is actually the premise, in which Chuck and Sarah pose as a just-married couple in order to investigate a suspicious neighbourhood. This actually forms part of the larger plot between Chuck and Sarah, in that both of them realise that it's the life they want to have together but never can.
 * More important than episode-by-episode missions, it's their overall background story. Chuck maintains his normal pre-spy life. Sarah stays close to him as a guide and guard, and for the first two seasons, their cover story to all his friends and family was that they were boyfriend and girlfriend.
 * Given that Sarah is the only female on their team, she's been paired with everyone except for Casey for missions like these, generally to play up the UST and/or jealous rage of Chuck.
 * Monk and Sharona, while investigating a marriage counseling retreat in the episode "Mr. Monk Gets Married". The counselor's response to finding out that they're not married is "Oh, thank God. Keep it that way."
 * Surprisingly for a show in which the main characters adopt new identities in every episode, Leverage does this rarely; however, in "The Mile High Job", Nate and Sophie pretended to be a couple while boarding an airplane, and then got into an argument over their past history while working on their cover story.
 * Hardison and Parker have also posed as a couple a couple of times. Most notably in "The First David Job" where they make out to cover for opening a door. Then there's "The Ice Man Job" where she's the girlfriend to his diamond merchant (the titular "Ice Man"), and finally "The Fairy God Parents" where they pose as newly-weds when looking at an apartment.
 * Hardison and Eliot also posed as a couple to get in and see Nate in "The 12-Step Job". Eliot was less than pleased.
 * In one episode of Blood Ties, Vicki infiltrates a fertility clinic by posing as a patient and gets Mike to pose as her husband.
 * In The Mentalist, Patrick Jane does this with his supervisor, Teresa Lisbon. He didn't precisely need to, and was more likely than not doing this to patronize her without fear of backlash.
 * Or, on the other hand, it could be because the writers know that there are crazy Jisbon shippers out there. Whom they like to taunt. With slow-dancing.
 * In Castle, Castle and Beckett pose as a BDSM-couple to infiltrate an exclusive high-class dungeon. Beckett takes a great deal of pleasure in expressing a desire to make Castle, cast here as the submissive boyfriend, 'squirm'.
 * Happens a number of times in Law and Order Special Victims Unit for Benson and Stabler.
 * In "Wildlife", Elliot goes off the radar while undercover as an animal smuggler. Olivia sneaks in to check on him, but is caught by the smugglers. She poses as his prostitute, which involves the two of them in their underwear.
 * In "Ace", they pose as an infertile couple looking to pay for a baby to bust a child-smuggling ring.
 * And in "Bombshell", they go undercover at a swinger's club as newbies. Strangely, this one has the least amount of tension between them.
 * Sue Thomas FB Eye had UST couple Sue and Jack do this several times. The first time it was treated as a big deal but later on it became common place.
 * Subverted in Undercovers, where the lead agents (Tish Jones and Luther) are actually husband and wife.
 * Lie to Me has Cal and Gillian go undercover as a kinky couple who want to make a porno to find a missing girl. This includes Gillian talking about liking bondage and the two sharing quite a kiss.
 * Bionic Woman (2007 remake). In "The List" Jaime Sommers and CIA agent Tom Hastings travel to Paris as a married couple. It doesn't help that they had sex in the previous episode and Tom can speak French, but Tom decides they need to focus on the mission -- leading to more distracting sexual tension than if they'd just slept together.
 * In Jack of All Trades, Jack and Elaine have to pose as lovers when infiltrating Marquis de Sade's BDSM-themed island resort. They also have to adapt a dom/sub relationship. No guesses who ends up which.
 * In one episode of The Sarah Jane Adventures, Clyde and Rani pretend to be a married couple of journalists. The faked marriage raises fewer eyebrows than the fact that they're supposed to be writers for a magazine aimed at senior citizens.
 * In the How I Met Your Mother episode "World's Greatest Couple", Lily ends up moving in with Barney. When one of his many women ends up seeing Lily walk in, she assumes that Lily is his wife and leaves. Barney then uses Lily as an excuse to get clingy women to leave.

Video Games

 * Guybrush and Morgan in Tales of Monkey Island: The Lair of the Leviathan have to fake being a married couple for Coronado de Cava so he would help them, as they were all trapped within a giant manatee and Coronado was neurotic and thought that Guybrush wanted something with the Voodoo Lady.
 * In Metal Gear Solid 4 Guns of the Patriots,.

Web Original

 * in The Red Panda Adventures, The eponymous Red Panda and his sidekick pose as a married couple in Episode 8: "Curse of Beaton Hall" to explore the mystery. They do so badly due to UST and their somewhat snark master-servant relationship. This is given a shoutout in Episode 49: "Nightshade" where, an enemy agent comments on how flimsy their disguise as a married couple is, right down to his sidekick still referring to him as "Boss."

Western Animation

 * An episode of South Park that portrayed all the major players of the 2008 US Presidential Elections (with the exception of Jo Biden) as a gang of ludicrously high class thieves, Barack Obama and Michelle Obama were portrayed as this. They really hook up at the end.
 * Happens briefly in the Avatar: The Last Airbender episode "The Headband" with Sokka and Katara, the latter even pretending to be pregnant. This being a Nickelodeon show, the Squickiness of their actually being brother and sister is not addressed.
 * Likewise in The Legend of Korra, Korra and Mako do the same in order to infiltrate an Equalist gathering.
 * Inverted on Young Justice, when Superboy and Miss Martian go undercover as brother and sister despite all the UST in their relationship. Icicle Jr. is naturally quite Squicked when they start making out.

Real Life

 * In his book The Greatest Battle (on the Battle for Moscow in World War Two) Andrew Nagorski interviewed two former members of an NKVD special forces unit who were ordered to go Undercover As Lovers (in the belief that a married couple would draw less attention) who, despite their initial awkwardness, ended up getting married for real.
 * Marriages between gay men and lesbians who were friends were common back in the day as a way to hide their double lives.