1. Bob has somehow dirtied/bloodied/soaked himself.
2. Alice walks by and, seeing Bob's plight, lends him a handkerchief.
3. The two might talk for a while, but Alice usually leaves before Bob has managed to clean himself up.
4. Left with just a dirty/bloody/soaked and borrowed handkerchief, Bob sets off to clean it and return it to Alice. Coincidence usually contrives to make this as awkward as possible, or Bob is already incredibly self-conscious about the whole affair, either because a. Alice is his crush, or b. he's aware of the trope's romantic implications.
Note that the scenario need not be Strictly Formula to count as a Returning the Handkerchief plot: the core of the trope is that Alice has lost something, and Bob has it. The lost item serves to remind Bob of Alice and/or encourage him to seek another encounter with her. It is not altogether uncommon for the handkerchief to go entirely unmentioned upon their second meeting; in which case, the handkerchief is a MacGuffin that disappears from the story once it is no longer needed.
For returning the handkerchief to make any sense, it has to be a washable cloth one (and it usually tends to be a fancy, decorated one at that), which is slightly peculiar considering the prevalence of simple paper tissues in modern society — especially Japan. This might contribute to the fact that the trope is largely discredited these days; if a literal handkerchief does appear in the story, the setup is likely to be parodied or not played entirely straight.
Western audiences might be more familiar with a similar comedy trope, in which Bob immediately offers the handkerchief back after being done with his business, and Alice politely rejects the sopping mess with a "keep it". The two forms likely evolved independently, however, and the classic gag is not this trope. Neither is a gentleman stooping to give back a hankie "accidentally" dropped by a Victorian lady, or a medieval knight being given one as a symbol of The Lady's Favour.
- The trope image comes from the Aneimo hentai anime, which is an example of the handkerchief-as-MacGuffin variant: it isn't seen after that last screenshot, but the encounter quite firmly cements the relationship between the two.
- Occurs in Lucky Star between Yutaka and Minami. As Minami was the Girl B, this trope was inverted.
- Averted in the chronologically last episode of The Melancholy of Haruhi Suzumiya, Someday in the Rain: Kyon returns soaking wet from a walk in the rain and Tsuruya cheerfully lends him a handkerchief in passing, but neither of the two think anything of it, and the handkerchief is never mentioned again.
- In D.N.Angel, Satoshi lends his handkerchief to Daisuke in the first volume; Daisuke gives it back in the second volume during a chapter that begins to explore Satoshi's character more. This is definitely played for the Ho Yay.
- Inverted, subverted and combined with an Indulgent Fantasy Segue in Bokusatsu Tenshi Dokuro Chan.
- This is how Ikki and Karin meet in Medabots.
- There's a mutant, and averted, version of this in Victorian Romance Emma. Realizing that a well-to-do caller on her mistress has genuinely forgotten his gloves, she rushes out to return them. Initially, she fails, but manages to actually do so later. A further mutation of this occurs when she and the man in question begin to start up a friendship, which looks to be very quickly heading for romantic territory when Emma tells him she's always wanted a silk handkerchief for her own. He buys it for her on the spot.
- Done by Dogged Nice Guy Takahara in Taisho Baseball Girls.
- In Hekikai No Ai On, Tatsuya starts to weep when he believes he'll never be a "man of high caliber" and Seine gives him a handkerchief. Later, he tries to invoke this trope just to talk to her because she says to him to stay out of her way.
- Occurs in episode 12 of Revolutionary Girl Utena between Utena and Anthy.
- In the Gacha Gacha manga by Tamakoshi, this occurs between Clara and Kouhei, although Clara is not the sweet type, the Kouhei got dirtied because she insisted on him fixing her bike.
- Parodied and discussed in Love Lab, where Maki has embroidered her contact info and a sob story about her grandmother onto a massive handkerchief in hopes of picking up boys.
- Parodied in a Fullmetal Alchemist OVA, where Sig returns the bear carcass (!) that Izumi drops.
- Momochi Yuka in My Monster Secret tries to Invoke this with Asahi, but at the last moment she realizes she forgot her handkerchief. So instead, she drops caltrops and kunai at his feet.
- Genderflipped in Pokémon. Ash left Serena with a handkerchief years ago and completely forgot about her. When she sees him on TV, she starts her own journey to find him and return it. She joins his crew afterwards.
- Gender Flipped in Blue Exorcist—Izumo and her friend are attacked in the changing room, and Rin is the first one to hear and come help. Since Izumo is in her underwear and freaked out by her inability to fight off the threat, Rin gives her his shirt so that she can quickly leave before anyone else sees her. She later returns it, freshly laundried, along with some complaints about how hard it was to clean.
- Pride & Prejudice (2005), Lydia attempts to do this with the soldiers marching through town but it fails as they don't even notice.
- Desiree Dubarry from Don't Lose Your Head tried this to get close to Duke de Pommefrites, except he picks it up and throws it away. When she tells him she dropped her hankerchief he refers to it as a smelly old thing.
- The smitten courtiers in Ever After try to invoke this trope—when Prince Henry falls into the crowd during badminton, he finds dozens of handkerchiefs in his clothes, placed there by hopeful young girls.
- In a Czech film Kristian (1939), an older guy invents yet another variant how to meet ladies in this fashion. He drops his own handkerchief, picks it up and forces it to the lady, insisting she must have dropped it. Sometimes the lady is confused, but the heroine Zuzana insists that it's most definitely not her handkerchief. At the end of the movie, the guy steps on a handkerchief that really was lost by a woman who this time is more or less of the same age as the older gentleman, and they seem to have a chance to hit it off. He's pleased that his scheme finally worked out, even though a bit differently than he had expected.
- There's a Running Gag in Robin Hood Czwarta Strzała, where Robin reminds himself he has to return Marion's handkerchief. In the middle of a duel.
- Walt Whitman's Leaves of Grass collection has a poem that references the "dropping the handkerchief in hopes of Mr. Hotness noticing it" variant positing that Nature itself is the Handkerchief that God has dropped to get our attention.
- In Les Misérables Marius finds a handkerchief left behind on the seat where Cosette and Valjean were sitting. He assumes it was Cosette's and makes a point of showing it to her to demonstrate his feelings. However, since the handkerchief was actually Valjean's, she doesn't have any idea what he is going on about.
- Early in The Three Musketeers, D'Artagnan meets Aramis while the latter has his foot on a handkerchief. D'Artagnan picks it up and hands it to Aramis, accidentally revealing Aramis's relationship with a lady and creating an opportunity for a duel.
- In The Lion, the Witch, and the Wardrobe the male beaver returns Lucy's hankerchief, which he got from Tumnus, to demonstrate that he can be trusted.
- A Darker Shade of Magic: Lila first gives Kell her handkerchief as a slight of hand to rob him, which he later uses as a magical focus to find her. She then gives it to him to link them together when they travel between worlds, and he once again uses to find her when they're separated. When they part at the end of the first book, he keeps the handkerchief as a memory of her, and wonders on more than on occasion if he could use it to find her again.
- When Richard is forced to impersonate a notorious womanizer with an incredible reputation for being really good in bed in the Legend of the Seeker episode "Princess", he complains about how many women in the Margrave's palace are dropping handkerchiefs in front of him.
- In the Smash Mouth music video for their cover of "I'm a Believer", the trope is subverted; the lead singer spends the video chasing after a woman who dropped her keys, only to return them without comment, even when the woman attempts to flirt with him.
- The Office subverts this in the Season 5 episode "Blood Drive"; after lightly flirting with a woman at the blood drive, he finds she left her glove behind. As the people running the blood drive are restricted from giving out personal information, Michael runs a Valentine's Day mixer at the office, advertising the missing glove in an attempt to attract her. But she never comes.
- Subverted hilariously in Chicago P.D. by Lt. Kelly Severide, crossing over from Chicago Fire. Wanting to see Lindsay again but not having a reason once his police business concludes, Severide steals a paperweight from her desk, then shows up at her apartment, claiming it fell into his pocket.
- Ressha Sentai Toqger uses a version of this, where General Schwartz drops a handkerchief of his and Greeta picks it up; she tries to return it but he tells her to keep it since he doesn't want it back. From then on, she's regularly shown clutching the handkerchief as a sign of just how bad she's crushing on him.
- Othello may be the earliest subversion. Cassio doesn't love Desdemona, but Iago makes sure he finds and returns her handkerchief, so as to frame him for having an affair with her. (It's worth noting that early critics were appalled to see a lighthearted comedy trope used to set up multiple murders, although opinion has softened over the years as critics have become more used to the concept of Playing with a Trope.)
- In Ib, if Ib has a high enough relationship with Garry, she can give Garry her handkerchief when he cuts his hand after burning Mary's portrait. This is how you can get the good ending in the games' Multiple Endings because the handkerchief plays a crucial role in curing Garry and Ib's Wistful Amnesia.
- In Metal Gear Solid, the character Sniper Wolf gives Hal "Otacon" Emmerich her handkerchief, which he later passes on to Solid Snake. Following Solid Snake's second encounter with Sniper Wolf, where she is fatally wounded, Snake places the handkerchief over Wolf's face after she dies.
- The Bug Pond: Played with. Leodegrance the assassin bug intentionally drops his hankerchief for Kid Katydid to pick up for him. She proceeds to stomp it.
- Parodied as a symptom of the "Love Sim Syndrome" in this Tsunami Channel strip.
- Homestuck: Rose's Mom loses her pink scarf in a meteor crash. John's Dad picks it up. After they were both transported to the Medium along with their respective children thirteen years later, he returns it. Romance ensues.
- In Barbie & The Diamond Castle, Jeremy and Ian find Liana's handkerchief after she and Alexa spurn their advances, and they use it as an excuse to follow after the girls.
- An old Bugs Bunny short has him advise his victim to start courting. He then dresses up as a woman, drops his handkerchief, and promptly freaks out (in his female persona, as if the guy had done something lewd) when the guy returns it and gets clobbered by a police man.