The guy in question is a little too young or innocent to appreciate the situation, and is more embarrassed than enjoying it (especially when it happens in public). In certain cases, the boy may be just old enough to appreciate the situation, but not old enough to control either his reaction to it or his mortification at same.
The poor boy is quite literally being smothered in the process, as the girl is reallywell-endowed.
In one Confused.com advert, Bertha puts Cara's face in hers.
Anime & Manga
Ciel twice in Ciel in Wonderland, a one-shot anime seemingly disconnected from the Black Butler anime. First by Paula, then Lan Mao, whom is a mushroom and her breast milk makes you grow or shrink depending on the size. Both incidents cause Ciel to squick.
This is basically a Running Gag; Kurumu Kurono, the resident member of the Unwanted Harem with Gag Boobs loves doing this to Tsukune, though she often nearly suffocates him because she forgets to let go. For his part, it's initially pleasant, but the frequent passing out part kinda blunts any potential perversion factor for him.
Mizore finds out firsthand how unpleasant that is when Kurumu gives her the 'accidental' version; Kurumu glomps her in thanks for bringing them to the Land of the Snow Fairies, not realizing that she's suffocating Mizora just like she always suffocates Tsukune. This, combined with the onscreen kiss after Kurumu saves her from suicide, and the resulting omake between the two, is one of the biggest reasons that this particular Les Yay has become a Fan Preferred Couple.
Her mother, Ageha, does this as well. According to Tsukune, she's even softer
In Airmaster, Mina is the main offender, though Maki has some moments as well, thanks to Mina and Renge.
Aside from the aforementioned scene, Chizuru, the class member with the most ample bosom, gets to inflict this quite a lot. The trope naming scene occurred when a swimming Negi got caught in her bikini topsomehow, and when a semi-feral InuYashaHomage showed up in her room, she simply marshmallow hell-brainwashed him. And has since more or less adopted the lucky dog, who wishes she wouldn't marshmallow hell him in public while his male friend is watching.
Oddly enough, Negi found one benefit from a situation like this. After a minor marshmallow incident with the amply endowed Shizuna-sensei, he inadvertently tricks one of his students (Kazumi, disguised as Shizuna) into revealing herself by noting that her breasts seemed smaller (whereupon the "teacher" protested that she had the "fourth largest in the class").
In the English version of the manga, Negi wins for getting wedged between Shizuna's boobs, and looking up with the request: "May I have a cookie?"
Makie actually pulls this on Negi in a chapter, despite being somewhat on the sugar-free side of the scale, so to speak.
In the Pokémon episode Hypno's Naptime, Ash gets hugged by a woman who mistakes him for her missing son, and he gets a faceful of bosom as the woman gleefully hugs him before he can explain she's got the wrong person. In the filler arc episode Pokémon Double Trouble, it happens to him again, for the exact same reason.
.hack//Legend of the Twilight loves doing this to Shugo, who has enough girl troubles anyway, especially when his sister catches him drooling at girls instead of doing something productive.
In another moment, one kid is musing about his dilemma — a double life between the real world and the game. He absentmindedly walks into a female character's breasts and ends his speech with the line, "And now I'm caught between two worlds."
Poemi of Puni Puni Poemi is frequently subjected to a variation on this where Shii Aasu rests her ridiculously enormous breasts on Poemi's head. Poemi's reaction is to panic and act like she's being quite literally crushed under their prodigious weight. Although the mechanics are a bit different and both parties are female, it's close enough that it was probably intended as a parody of or reference to this trope. (It is made clearer, at least in the dub, when another Aasu sister reminds Shii "what happened to the cat".
Poemi: Why are there huge boob like things on Kobayashi's head? note Poemi is a Third-Person Person that refers to herself by her voice actress' name.
Kűgen Tenkou does this to Noboru Nakagami in the third episode of Wagaya No Oinarisama when Noboru relents to her wanting to be shown around his school.
In Mahoromatic Shikijo also rests her Gag Boobs on Mahoro's head when they go to a public bath together. However, she does this more to taunt her small-breasted rival than any thing else. After all, this pedophile is a Shotacon, not a Lolicon.
In Grenadier, Rushuna uses this to hide Yajiro from enemy soldiers while in a hot spring (like Negi, he almost drowns, but unlike Negi, he's old enough to enjoy it). It's also her patented approach to negotiation, though sometimes she just goes for a regular hug.
In a variation that can only be described as... odd, the final episode of Gravitation's anime features Sakano calling in a gang of sumo wrestlers to smother an especially depressed Shuichi.
Excel Saga: This makes an appearance in the manga version, in Professor Shiouji's reunion with his mother.
Miwa: Why, other than your windpipe being blocked, don't you say, "Mom, I'm dying for your love"? Shiouji: I... I'm dying...
She has done it to Umi and "Teriha" too. Neither time has it been innocent.
And at the end of a recent episode, Hitsugaya gets this from Rangiku again. He's greeting his best friend Momo Hinamori, then Rangiku shows up from behind and her boobs hit him on the back of his head (this time it's a genuine accident tho), and he ends up pretty much flung towards Momo, in such a position that it's rather reasonable to think he may have ended up landing on her much smaller boobs as well.
Subverted and played straight in the Haunted Junction manga. When Kazumi and other guys are beaten up and brainwashed by the villainess Blue Spot Girl, Haruto summons the female ghost Toilet Hanako and she snaps Kazumi out of it when he accidentally buries his face on her chest. The subversion comes right afterwards, as the Marshmallow Hell debrainwashing only works on Kazumi, who's been infatuated with Hanako for a long time; she notes how her and Blue Spot's supernatural abilities are different, therefore she cannot do anything against her. It takes Red Mantle taking his mask off to rescue the rest.
In Gulliver Boy, Teen Genius Edison's adoptive mother always hugged him to her very ample chest. After parting ways with her, Edison constantly hugs Misty and buries his face on her also huge breasts, and (weirdly) she doesn't mind at all.
Inverted: Mikoto, who's rather short by anyone's standards, likes to bury herself between Mai's bosom whenever she goes in for a hug.
In the Mai-Otome manga, Erstin likes to hug Manshiro this way, and it's called "Bust Impact" and described the same way as one might describe an attack from a typical Shounen. It's even given variants like "Bust Impact Returns" and "Bust Impact Forever". note This is because it really is an attack, presumably toned down so it doesn't do any damage (maybe it tickles?). She uses the full version of it against Arika in their fight, and it almost completely wipes the latter out.
In Mai Otome Zwei, after Mahya rips off Arika's top when she tries to slip out of the bath to look for Mashiro, a drunken Anh Lu gets up and offers to help Arika cover her exposed breasts, pulling her down onto her chair and putting her face into her breasts.
Although Kitagawa from Doki Doki School Hours usually makes sure she doesn't smother her beloved teacher Mika, she can't always help it since she's so well-endowed and the object of her affection is so small.
Kanokon probably breaks the record for the fastest time, when Chizuru smushes Kouta within five minutes (counting the Op). Perhaps boys should start avoiding (or seeking out) girls named Chizuru on general principles.
In Eyeshield 21, Mamori thinks Sena has been beaten to unconsciousness and clutches him protectively to her chest, consequently smushing his face right between her breasts. Surprisingly, for this trope and this genre of manga, it's quite understated and nothing ever comes of it.
Sanji was once rescued from drowning by a mermaid who carried him to the surface with his face pressed to her bosom; it gave him a nosebleed that lead her to think Sanji must be dying from the pressure change. Although it's kind of a subversion because in Sanji's case, it was more like Marshmallow Heaven.
Also, when Nami and Usopp first reunite after the Time Skip, Nami's greeting involves grabbing his face and jamming it into her breasts. Usopp is actually taller than Nami contrary to the trope description (they're about the same height when Nami is wearing high heels), so in this case, the Marshmallow Hell was probably totally consciously done on Nami's behalf.
Action Girl and Team Mom Erza has a habit of clutching other characters to her bosom whenever she's relieved at their safety or proud of their accomplishments. Unfortunately for them, she wears breastplate (ha) armor at all times. Ouch...
Accidental variation: Natsu got a faceful of Lucy's breasts once when he caught her from falling out of a tower. Being a Chaste Hero, the only thing he was worried about was his air supply.
When Kamina and Simon are ambushed by Kittan and his three sisters in Episode 4, eldest sister Kiyoh (who let's just say could give Power Girl a run for "bustiest blonde in media") uses this on Simon. Particularly hilarious, since she points out that Simon is the perfect height for it.
There's also the very first episode where Simon gets a face full of Yoko boobage after crash landing the Lagann — twice. While the first one probably counts as a Funbag Airbag, the second is gratuitous Marshmallow Hell as Yoko was trying to get him to duck, but looks like she's going out of her way to make sure her boobs were right in his face.
Heck, Boota takes the cake. Every time Yoko is present in her usual Stripperific outfit, Boota immediately leaps over and makes himself comfortable in her cleavage. She's only mildly surprised the first time (prompting Kamina to remark "Say... which one do you think is tastier?") and completely ignores it afterwards.
In the High School AU of Gurren Gakuenhen, Yoko (in a sailor suit) does this to Simon... and forgets about him as plot happens. He finally surfaces three pages later.
After one of Lala's machines accidentally shrinks Rito to about 5 inches tall, she hides him by carrying him around in her cleavage all day. Naturally, she's not wearing a bra. He nearly gets suffocated and/or squashed multiple times.
This incident exhibits the other end of the spectrum.
Rito is subjected to this so much that it probably isn't a far stretch to say that his hands and head are breast magnets.
This happens with Chrono and Satella. In the manga, she does it on purpose, because of her shotacon complex and the fact that she was drunk at the time — Luckily, Chrono is Really 700 Years Old. In the anime, he accidentally faints from a fever and lands right into Satella's cleavage. Since in the anime Satella doesn't like little boys in that way, he gets punched in the face for his trouble. Later in the episode, Rosette faints into Satella's breasts, as well.
Also in the manga, Azmaria bursts into tears and falls into Rosette's breasts while they're taking a shower together. Azmaria didn't mean this to be titillating in any way, but there's a good chance that Moriyama, the mangaka, did.
Done in Flame of Recca. Made worse by the fact that the one doing the hugging was a being made of extremely hot fire.
The huggee doesn't even to be human to invoke this trope. Sphinx, Index's pet kitty in To Aru Majutsu no Index, gets to know Index's new friend Hyouka in a very close, soft kind of way. Sphinx seems taken aback by the whole thing, apparently preferring the flatness of his owner.
In one of the manga arcs of Higurashi No Naku Koro Ni, Mion and Rena like doing this to Keiichi. Usually while yelling "Squish Attack!" This doesn't seem completely innocent.
This is parodied in a Zombie Powder omake with Wolfina and Elwood, where Elwood gets mushed into her h-cup breasts so many times that he gets whiplash.
In the Shuffle OVA (OVA because most of the fandom rejected Memories), a shrunk down Rin Tsuchimi tries to get Sia's attention. By leaping from a wooden plank and landing smack in her cleavage. The other girls were not amused.
In one Fate/stay night doujin (Heaven's Failure), a genderflipped Shirou in Ilya's body (thus having her dubbed Emilya von Einzbern) is hugged by a tearful Sakura in this manner.
In Rebuild of Evangelion 2.0, Shinji is introduced to Mari this way when she parachutes onto him. It is one of the times this trope looks seriously painful. He was lucky not to have a concussion despite the "padding".
Hayate the Combat Butler has Saki do this to her charge Wataru. He makes it clear that he is of age to be thinking of things like that and protests. Saki realizes what he's objecting to and releases him to berate him about watching adult videos (they live in the video rental store he owns).
In Change 123, the main character (characters? it's confusing, the main character has 4 well, 5 personalities) is told that she cannot be a warrior because of the awkward mounds of flesh on her chest. She proceeds to attempt to smother the offender with them in an attempt to prove that they can be used as weapons.
In Dennou Coil, Tamako hugs Haraken to her boobs, in order to calm him on his guilty feelings for Kanna's death.
A subversion of this happens to Rana quite often, as his Action Mom Cattleya fights while holding him with the other arm. So often times when she loses balance Rana gets a face and hand full. The subversion is that there's no perversion factor, Rana just loves to be around his mom.
Played straight in an episode of the anime, where Echnida yanks him close while she's taunting Ymir. Rana is not thrilled about being buried in her chest and flails until she releases him.
In Girls Bravo this is one of Lisa's favorite tactics when trying to seduce Yukinari — despite the latter's severe girl allergy.
When a student appears to be contemplating suicide by jumping off the school roof in Gokusen, Fujiyama-sensei offers to catch him if he really wants to jump. She says while she may not survive his landing, her boobs will probably save him. Other students unsuccessfully try to take her up on that offer.
Again with Fujiyama-sensei when Uchi attempts to run off during the class trip, she grabs him and pulls him tight. And he promptly passes out.
In WORKING!!, Souta's oldest sister Kazue can't withstand Popura's Cuteness Proximity and gives her this treatment, much to Popura's confusion.
In Strike Witches Lynne does this to Yoshika after they successfully took down their first Neurois.
In the "Fighting Wings" Special of Ah! My Goddess, Belldandy, of all people, does this to Keiichi when the latter is returning to consciousness after the battle with the Angel Eater and trying to get back on his feet. It is purely by accident, although it is still rather amusing to behold.
Midori Days goes to a higher level when a drunken Lucy Winnlad stumbles into Seiji's room with barely anything on and sleeps with him, causing Midori, who is Seiji's right hand, to struggle with breasts bigger than her.
Keade from Iketeru Futari got it so bad from his mother when he was a baby that it gave him a breasts phobia. Needless to say this kinda complicated things for his potontial love interest, Yuki.
Something of a meme in a corner of the Yu-Gi-Oh! GX fandom, taken from the end of the third season when Juudai falls, unconscious, against Yubel's chest. A poorly-drawn set of in-between frames gives the impression that he faceplanted directly on the one breast she's got.
In Happy Lesson, Mama Satsuki does this with her special move she reserved just for Chitose, "The Booby Trap". Mama Kisaragi copied this with the rest of Satsuki's personality when a failed experiment caused a Body Swap. Oddly, when the technique is performed the breasts of the user inflate to properly conceal around the victim's head, while the victim is facing away from the suffocating tits. It's that powerful of a move. Did I mention she's the Gym Teacher From Hell?
Episode 12. Taro's three personal maids Glomp him while he's taking a bath and they're all naked.
Episode 14. Konoe doesn't notice her breasts bouncing against Taro's face while she's pressed behind him while teaching him martial arts moves.
Dragon Crisis has Eriko do this to her cousin Ryuuji in the very first episode.
In episode 4 of the second season of Baka To Test To Shoukanjuu, Shouko does this to Yuuji to confirm once and for all whether or not he really doesn't find her attractive. Though Yuuji feebly denies he is enjoying it, his Summon leaping for joy (the upgraded Summons speak and reveal their summoners' thoughts and repressed feelings) reveals that Shouko's physical charms are not lost on him.
This has happened to Lupin of Lupin III several times, being the pervert he is most of the time he enjoys it, one of the exceptions was when Fujiko's overweight aunt hugged him and pressed him into her breasts he struggled to escape.
In episode 6 of Tantei Opera Milky Holmes, Sheryl actually gets stuck in Henriette's breasts and tries to struggle to get out, for about 20 seconds.
In episode 20 of Slayers, Amelia sees a Not What It Looks Like situation involving Gourry and Sylphielnote she was actually just casting a healing spell on him after a fight with Zangulus and tries to stop Lina from seeing it, so she grabs Lina's shoulders and raises herself up to block Lina's view with her chest. Lina is annoyed by this, both because she can't breathe and because Amelia's breasts are larger than hers.
Berserk managed to play on this trope in a horrific and squicky manner. During the Eclipse, Band of the Hawk member Corkus managed to outrun the demons and was steadily losing himself, convincing himself that it's All Just a Dream. He found a naked woman nearby and promptly puts his head inbetween her ample breasts... only for the woman to shortly reveal that it's a nasty demon that has breasts and proceeds to devour him.
Rental Magica started one such scene with Kuroha trying to comfort Itsuki, her breast swaying right before his blushing face. But then, she's a ghost. As in, not fully corporeal. So this was played a little... farther than usual.
In Sekirei, Minato is an occasional victim of this, thanks to his incredibly well-endowed harem. Competition between Musubi and Tsukiumi often involves him being squished dangerously between their breasts. Kazehana takes the cake, though, having the largest chest in the entire series and a tendency to shove his face into her cleavage when excited.
Astonishingly, Power Girl herself is nearly on the receiving end of one of these during a supervillain-induced hallucination.
In Hate, Buddy takes his elderly dad to a strip joint and is shocked to find him with his head in a dancer's chest. Thinking he's passed out, Buddy rushes up to the stage to get him, but instead he says to Buddy, "Can't you see I'm having the time of my life?"
In 2011's Hack Slash #4, Cassie does this to Vlad to get him to snap out of his slasher-induced altered state of mind.
She also does it twice in You Got HaruhiRolled!: in the first time, the Alien vs. Time Traveler arc, she accidentally does this to Taniguchi when Yuki knocks him into her. The second time is during the anniversary chapter, where she quite deliberately does it to Fujiwara, in an attempt to smother him.
Subverted in Aeon Entelechy Evangelion where instead of Misato's breasts Shinji got a facefull of Misato's hard not-squishy front armor.
In the Sly Cooper fanfic Lament of Carmelita, the character Karla Chintzy uses this when trying to seduce Sly Cooper, though fails due to Sly only being interested in Carmelita Fox. She tries this move several more times again in the sequel Dawn of Progeny (albeit as an attack instead of a seduction tactic); first against Guru when she attacks the protagonists after being awoken from cryogenic stasis, then in a sparring session with Sly's son Conner Cooper, then again during a fight with a clone of Carmelita. Each attempt is equally unsuccessful, as she invariably ends up being hit by a counterattack before being able to subdue her opponent.
In the Soul Eater fanfic Winter Waltz, Patti does this intentionally as a way to knock poor, unsuspecting guys unconscious. Naturally, Kid is shocked.
At the end of Castle in the Sky, Ma Dola catches Sheeta in a big hug to comfort her over the loss of her pigtails. Sheeta's more upset about getting poked in the eye by stolen jewelry (in Victoria's Secret Compartment) than she is about getting smothered in a middle-aged woman's bosom.
Happens momentarily to Kaneda pushing his way through a crowd in AKIRA.
Believe it or not, a Disney animated feature used this trope! In The Black Cauldron, young would-be warrior Taran, Princess Eilonwy, and minstrel Fflewddur Fflam travel to the house of three witches, trying to get the title cauldron before the movie's Big Bad, the Horned King, can get his hands on it. The fattest and most voluptuous of the three witches develops a crush on Fflewddur, and at one point, proceeds to bury the horrified, skinny man right between her breasts. But wait — there's more! One of her sisters, tired of this lovey-dovey display, turns him into a frog in preparation for eating him... and the frog-Fflewddur gets completely smothered in the cleavage, desperately trying to wade his way out of there for several seconds of screentime. And that's just one of the two reasons why this is the first fully-animated Disney movie to ever get the PG rating...
In the film Fievel Goes West, there's one scene in particular where this trope occurred. As soon as Fievel enters into the saloon, he proceeds to nab a fork and plunge it into the... *ahem* hindquarters... of Cat R. Waul, causing him to jump several feet in the air, right through the roof above him (which was in turn the floor of the human saloon above them). As soon as he emerges, he is quickly grabbed by a rather affectionate woman who proceeds to put him through a Marshmallow Hell before he barely manages to escape and descend back into the saloon.
In The Last Unicorn, Schmendrick gets this treatment from the tree he's tied to, after his magic makes it decidedly more anthropomorphic.
Schmendrick: Oh, God, I'm engaged to a Douglas Fir!
The '70s Chesty Morgan film series, which starred the eponymous Chesty Morgan, an Danish stripper with large breasts (something like a triple J cup) as an assassin who would seduce her targets and then smother them to death in her cleavage. Seriously. SlightlyNSFW.
And the name of the movie? "Deadly Weapons", of course!
This takes place in Police Academy 3, too: a small Japanese student attempts to seduce Callahan, his hardass Amazonian drill instructor. Callahan immediately pulls him into the bedroom, and then says, "In America, talk is cheap!" She then tackles him down to the ground with his face in her breasts. His (muffled) comment? "I love America!"
In the obscure European movie The Real Shlemiel, the Kid Hero's huge aunt is always hugging him this way. And, when a goblin is in the front pocket of his shirt is almost crushed by Aunt Sarah's cleavage. So, the goblin has to jump every time he realizes that Aunt Sarah is about to hug Aaron.
Happens to Austin Powers in The Spy Who Shagged Me, when Felicity Shagwell borrows a pair of binoculars still attached to his neck.
Austin: Hello, mummy. Mummy, can I have some chocolates? I want some Mars bars! Don't smack my bottom, mummy... Oh, sorry, love. Got caught in your dirty pillows.
Happens in one scene of Transylvania 6-5000 when Odette the sexy vampire lady (played by Geena Davis) does this to Ed Bagely, Jr in the library.
Odette: Face to my breasts! Tell me you want me, too!
Young Mitch: Note to self- Aunt Phyllis is your aunt!
The Narrator (Edward Norton) of Fight Club gets pressed between Bob's bitch-tits during a testicular cancer support group. The look on his face while being in Bob's bosom is hilarious.
When the guys try to set up a bachelor party for Jim in American Wedding, they hire a stripper in a police uniform who has a tendency to punish people via this method. She even punishes Jim's MOTHER via this method!
Happens in Honey, I Blew Up the Kid when Diane volunteers to be hit by Wayne's shrink ray while it's in reverse in order to calm Adam down (he's crying after Hendrickson tries to shoot at him, but misses and hits the giant electric guitar, which hurts the giant boy). It just so happens that Nick and his girlfriend Mandy are in the kid's front pocket.
In the MST3K classic Village of the Giants, a guy is picked up by a giantess, who danced with him pressed to her gigantic bosom, clinging to her bra straps for dear life. Quoth Mike Nelson, "First base is larger than I remember!"
In Fellini's Amarcord, the young protagonist Titta gets pressed against the huge breasts of the buxom tobacconist after betting he could lift her (and is encouraged to suck on them, but end up complaining he can't breath).
Ulla does this to Max in the 2005 version of The Producers. Not only that, but Max also goes back for more a second time in the same hug.
In 9 to 5 Dolly Parton imagines doing this in a Dream Sequence as revenge on her sleazy boss who won't stop harassing her.
Inflicted by Suzie (played by Kylee Nash) on Nate in MILF (2010), who is probably enjoying it.
Occurs in Thunderhead, by Douglas Preston and Lincoln Child, when a male scientist falls during a rock-climbing accident, and is caught by a certain generously endowed female scientist below him, cushioning his face in a very sensitive area.
Parodied in Wyrd Sisters. After the fool is stabbed... with a fake stage knife, he ends up in Magrat's bosom, such that it is. There was some interesting dialog as they end up actually arguing about whether or not he's dead since, on the one hand, he thinks he's in heaven because there's boobs in his face, and on the other hand, dead people don't need to breathe.
This happens in the novel Cold Mountain, when Inman and Veasey are staying with a man and his several wives and offspring. One of the women, named Lila, does this to him because she wants to have sex with him. Fortunately, although they are (involuntarily, in Inman's case) married, it doesn't happen.
Flashman in the Great Game. This happens to Flashman after he's rescued from torture by an Indian queen. Unfortunately for the permanently-randy Anti-Hero, his hands are tied.
In the Xanth novel A Spell For Chameleon, Bink is rescued from an angry centaur by said centaur's girlfriend, who pulls Bink close to protect him, pillowing his head on something. When Bink turns around, he's face-to-not-quite-face with those "pillows."
This happens to Gus once on Psych.
Lauren Zizes does this to Artie on Glee during "I Know What Boys Like."
Used as a weapon in an episode of The Nanny. C.C. (who hates Max's children) tells the youngest child Grace that the only reason Fran spends time with them is because she's paid to (not true, Fran does love them.) Grace runs away from home to Fran, and when Max finds her, she begins to tell on C.C., who then grabs her in a huge hug to shut her up.
In an episode of Star Trek: Enterprise, Captain Archer winds up tied to his "breast officer" T'Pol and, in course of wiggling free, they wind up dancing cheek to chest. This is slightly lampshaded by the fact that, when Archer realizes that he will have to end up chest to cheek with her, he looks up at her and she gives him the "yeah, yeah, yeah, go on..." eyebrow raise...
An episode of the Spike TV series 1000 Ways to Die shows a man who was killed when he was crushed and smothered under a particularly heavyset woman he was making love to.
Miss Piddlin, the lunch lady character on All That, would often hug students this way (Though the first time could've been accidental, as the character was played by Kenan Thompson.)
Lampshaded twice, from Olive and Chuck, on Pushing Daisies when Olive comforts a boy who recently lost his mother:
Olive: There, there. (pushes him over to Chuck) Chuck: No, not here, here!
This happens to Joey once on Friends. When he stars in a show (full of Stylistic Suck), Phoebe makes him think he's done a great show by hugging him in a very special way. Used again in the same episode when Joey's show gets cancelled. This time, both Phoebe and Rachel do this.
In Band of Brothers, Perconte gets this from a matronly Dutch woman during the liberation of Eindhoven. Sgt Lipton yanks him away, whereupon Perconte staggers off with a stunned expression on his face.
In an episode of House, House wonders why someone would try to commit suicide by electrocuting themselves. He lists off a number of other ways to kill yourself, rounding it up with: "Bury yourself alive in Cuddy's cleavage."
Darla did this to Angel when she sired him. She drank his blood, then cut herself between the boobs and pushed his face to her chest to make him drink her blood.
This is actually what Dracula does to Mina in Stoker's novel, but without the titties (also, Mina doesn't turn right away, giving us an Ill Girl sort of plot where the heroes have to destroy Dracula and end the taint before she dies).
And it was also (implied) when Drusilla sired a resurrected, human Darla - we don't see the whole thing, but Drusilla also cuts herself there. It might be all female vamps sire new vamps like this. In a sense, it's symbolic - the sire is like a parent and the new vampire like a child, and what does a mother do when her baby is born ...? Essentially, it symbolises a new birth.
Happens in Just Shoot Me when Dennis' fiancée hugs him when he proposes.
Lexx: Xev delays Stan from asking the Living Ship to destroy an inhabited planet by knocking him down and smothering him while she argues against it.
In a Seinfeld episode, Elaine sends out Christmas cards with a photo of her accidentally baring a nipple. George is upset that everybody she knows got one, except him. Elaine gets angry, and rubs his head on her breasts. Made funnier in that George was utterly unaware of the nipple issue when he mentions it, and Elaine hollers, "You want a Christmas card? I'll give you a Christmas card!!!"
An episode of That '70s Show had a wrestling match between Eric and Donna, which ended when Donna put Eric in a bearhug. She asks why he isn't fighting back, and Hyde points out why he wouldn't want to.
Happens to Joy with Darnell's "big" and overly excited sister in the My Name Is Earl episode "Joy's Wedding."
With a Scene from a Hat entitled 'Songs from a musical about breasts' and a master in Refuge in Audacity like Colin Mochrie, it was probably inevitable that he'd reference this trope on Whose Line Is It Anyway?.
"I like to stick my head in...GBBBBBRRRRRR!!!!!"
In The Suite Life on Deck, Carey does this to Cody(sort of) when he's about to leave for math camp and she tells him to call her in case there is an emergency and hugs him tight to her chest.
Cody: Emergency! Can't breathe!
The Tom Smith song "Death by Woobie", which originally had a slightly different name.
Professional Wrestler Jillian Hall has more done this a few times against mostly female opponents to humiliate, disgust and or attempt to smother them. One memorable time was in mocking Ashley Massaro, who was revealed to be on the cover of an up coming Playboy magazine. This actually doesn't always get a positive reaction from the fans in attendance, as Jillian has a habit of making the audience hate her. Though this is more for the fact that she could kill several small children with her voice. At least she doesn't turn to other tactics, like fellow female wrestler Mickie James...
There was an image of a valet on an indy show who basically had real life Gag Boobs. Her wrestler's opponent was lying with his head on the apron facing up, and she dropped her breasts on his face as a variation of the old "manager choke from outside the ring" spot.
In The Legend of Zelda: Majora's Mask, one of the sidequests involves delivering milk from the ranch to the bar, in exchange for which you get the mask that lets you into the bar, which lets you enter the milk bar that serves the very useful Infinite Magic potion. Due to the nature of the game, it's possible to do this sidequest more than once, even if you already have the Mask. If this is the case, the moderately well-endowed girl from the ranch picks up young Link for a hug, resulting in Marshmallow Hell. Particularly amusing is the narrative note that, "You feel all warm and fuzzy inside! You could get used to this." What's even more amusing is that the note has an Accidental Innuendo typo, "You feel all warm and fuzzy! inside!". The thing that makes it funnier is that she literally just takes him and plants his face right into her chest and holds him there for a few seconds. She doesn't seem to have any qualms about doing this, she makes no attempts to avert this by kneeling down so she's eye-level with him. Link himself doesn't even try to wiggle free! Here is the picture.◊
Laharl has the misfortune to be on the receiving end of one by Jennifer — misfortunate because he's literally allergic to Gag Boobs, and the proceeding freakout only prompts Jennifer into a impromptu sex-ed lesson. The thoughts of bystanders could best be summed up as, "WTF, dood?"
There's also Disgaea 3, which has a girl-on-girl example (quoted above) where Sapphire picks up the tiny, fun-sized Raspberyl and subjects her to Marshmallow Hell. Unsurprisingly, this has sparked a pairing.
Asuka's ending in Tekken 5. Featuring her cousin Jin.
And in a different place, Sophitia leap onto an opponent's face and muffle them with something else, turning her legs to break their neck in a throw rather appropriately called "Heaven and Hell". Considering what goes to the face, maybe this is an example of Apple Pie Hell?
In Tech Romancer, during a scene in Pollin's storyline, Pollin transforms herself into an older (and bustier) form, and gets in an argument with Pulsion's human form Kei about whose bust size is bigger. With mutual love interest Junpei... caught in the middle. The US version unfortunately censors this, changing the written dialogue to them arguing over who loves him more.
Discworld has this happen to Rincewind in a randomly-triggered cutscene — typically taken to the absolute most ridiculous extreme — as The Lady's hand comes down from the heavens, plucks up the hapless wizard and hides him in her truly gigantic cleavage. It's all a bid to win whatever game the Gods are currently playing, but Fate calls her on it. Much to Rincewind's frustration.
In many games, many characters can perform this as an attack called "Puff Puff" that will usually cause the victim to miss their next turn. In Dragon Quest 6 and 7, male characters can also do it, although it has a slightly different effect (it does damage).
Speaking of Dragon Quest, this gets teased a number of times. In Dragon Quest III, a cute girl offers to give you one of these. You are then taken to a dark room, and when the lights come on, you learn that the person that gave you the "Puff Puff" was the girl's incredibly burly father. It also gets teased in Dragon Quest VIII, although a bit less creepy, as the girl doing it is simply using slimes. And it gets teased yet again in Dragon Quest IX, although this time the girl is using sheep's asses.
Boobie Lady—er, Litchi often unwillingly does this to Taokaka, who is more than happy to enjoy her "nice comfy airbags." She also willingly stuffs Carl's face into her cleavage, during his cooldown hug during CS's story mode.
In the past, Nine (Kokonoe's mother) did this to hersister Caelica.
In Grandia II, Milenia does this to Roan when they first meet.
Near the beginning of Boktai 3, Lita uses a "Chest Attack!!" to snap Django out of his amnesiac state. This fails because [A] Lita doesn't have enough chest for an A-Cup and [B] she punches out skeletons bare-handed. By the time the "attack" ends, Django is 1 HP from his last save file. She does provide free medicine to fix him up, however...
In Rune Factory 3, if you decide to make Pia your love interest, she does this to Micah after he reveals that he's a human/monster hybrid. He eventually passes out due to lack of oxygen, and murmurs that 'at least I died happy...',
You does this to Kid in Ever17, although it is only mentioned in the text and doesn't have an accompanying visual.
Kurugaya does this to Kud in Little Busters, causing the poor girl to quickly grow dizzy from lack of air and Kurugaya to hurriedly adjust her, commenting that hugging her from a 45-degree angle is the best.
In this strip of the Touhoudoujin4komaLife Of Maid, Chibi Yuyuko drinks the milk of a cow that defeated her in a battle of Moe (I wish I was making this up) and promptly turns into her non-chibi form, complete with large breasts, before giving Youmu a great big hug. This turns out to be a dream (a good dirty one, to be precise) that Youmu is having.
ThisEvil Inc. episode is a special case. There the hell is mainly from being crumpled.
Happens here in Juathuur, but the characters involved are siblings.
In the episode "Insane in the Mainframe," Fry is let out of a robot insane asylum, brainwashed into thinking he's a robot and begins beeping. Devastated, Leela embraces Fry, pushing him up against her chest, causing him to beep more rapidly.
In the episode "Why Must I Be a Crustacean in Love?", a female Decapodian named Edna, discovering that Fry had been teaching Dr. Zoidberg how to woo her in an attempt to help Zoidberg win her affections, becomes enamored with Fry and lures Fry to her apartment to try to seduce him. Zoidberg happens in upon the two as Edna is forcing herself on Fry and Edna professes her love for Fry, whilst pressing his face into her cleavage, muffling Fry's attempts to object.
In one episode of Pinky And The Brain, during a parody of Man of La Mancha, a woman hugs Brain and promptly loses him in her cleavage.
In the Justice League Unlimited episode "Dark Heart", Wonder Woman needs to carry the shrunken-down Atom into the midst of a horde of dangerous robots. While fighting her way through them with the Atom in one hand, Wonder Woman decides that she needs both hands, and promptly tucks the inch-high Atom into her cleavage. He wisely says nothing (though he was supposed to in the original script), but looks quite pleased. According to writer Warren Ellis, when he questioned whether they would be able to keep the cleavage scene someone on the production crew assured them they would keep it in, reportedly saying, "We will defend the cleavage with our lives!" God bless them.
The boys in South Park set this up as part of a plan to snap Chef out of The Super Adventure Club's brainwashing. The woman in question is a very obese stripper. When her cleavage doesn't work at first, she then puts Chef's face between her asscheeks.
Francine of American Dad promptly deals this out to Snot when she believes he's drowning at the bottom of a pool, even though he was cosplaying The Little Mermaid with Steve, Barry and Toshi (Specifically, he was Sebastian). Oh, and this kicks off an Escalating War between him and Steve when Steve vows to get even by getting the same thing with Snot's mom.
A running gag in the earlier episodes of Rocko's Modern Life involved Rocko winding up stuck between Gladys the Hippo's breasts, every time he would do so she would yell, "How dare you!" and beat him up.
Happens very subtley to Woody Woodpecker in the cartoon A Fine Feathered Frenzy. He tried to run away from Gorgeous Gal who was a large elderly widow crow that fell in love with him at first sight. The Woodpecker opened a door, ran through it and bounced when he buried his face into her chest. She grabs him and Woody's head and hands are right where her large breasts would be (accentuated in other scenes), but since she is really overweight and five times bigger than the Woodpecker it isn't obvious right away. Gorgeous used this opportunity to kiss Woody on each cheek. He escapes even though it's not too long until she grabs him and plants more kisses on his lips.
In the Ren and Stimpy Adult Party Cartoon episode "Naked Beach Frenzy", Stimpy blocks Ren's view of a woman undressing at the beach, in anger he flings him out to the beach where he winds up stuck between the woman's breasts, he struggles to escape while she hugs him and her friends gather around and do the same to him, Ren gets jealous and tries to get them to do the same to him, but they mistake him for a crab and they get a lifeguard to beat him up.
This sometimes is used as a tactic by female players in Humans vs. Zombies in order to either score a silent infection against a human, or in order to silently kill a zombie.
At many Ren Fairs, "serving wenches" will do it as a joke. Particularly if the man in question is behaving like a cad. They even have a name for it, it's called a woobie.
Happens constantly in strip clubs. Some years ago, an extremely huge-busted model/stripper named Tawny Peaks was sued by a club patron alleging he suffered severe whiplash from one of these.
This is a favorite tactic of many Drag Queens around straight men in the audience when they interact cabaret style, especially one in the Boston area who regularly includes this as part of his act.