Brooke Shields had a famous commercial with the statement "Nothing comes between me and my Calvin Kleins".
Anime & Manga
Mello in Death Note has slits down to... well, you know in some official artwork
In Heaven's Lost Property, anime and manga, Sohara goes around like that for a whole episode/chapter. Against her will. She's also unable to wear any underwear... anything whatsoever in fact... and if she tries it flies away. Literally. That's just the kind of show it is. Never give magic powers to a perverted protagonist.
Happens to the heroine of Ghost Talkers Daydream. One of her day jobs is as a columnist for a porn magazine (the other is as a dominatrix at a BDSM club) and at one point she's reminded that the prize that the magazine is supposed to send to a reader is her panties. Since she hadn't brought spares, she leaves the ones she was wearing. Obviously played for Fetish Fuel since, a few minutes later, she stumbles on her high heels and falls down, giving a male witness an unobstructed view of her pantiless crotch.
Early in Dragon Ball, Goku once removed Bulma's panties while she was sleeping (and freaked out because she had no balls like his grandpa) and she remained unaware of it. When Muten Roshi asked to see her panties in exchange for his Dragon Ball, she lifted her skirt in front of him. It was only after she and Goku returned to their capsule house that she realized she had been going commando since the previous night, and it only got worse for her when she realized what Roshi really saw. She let Goku have it upon finding out that it was he who took them off.
In one episode, all the girls are wearing Kimonos and Maria is squirming uncomfortably. Someone asks why. She says that "she's been forced into wearing some". People assume she means underwear, but no, she's referring to socks.
Kanzaki Kaori from A Certain Magical Index wears no undergarments whatsoever (bra, panties, or socks). When Touma destroyed Index's outfit when they first met, she wasn't wearing undergarments.
One episode of Grenadier had Rushuna get her panties shot off. The poor girl ended up running around the battlefield with her hand on her crotch while wailing "NOOOOO!!!" (Bad enough she ran out of ammo before it happened.)
According to Akamatsu himself, Tamaki goes commando because her tail makes panties very uncomfortable for her, so she decided to just be practical about it. As a matter of fact, her entire race goes underwear-less for this reason.
Actually confirmed in the series itself. At some point Shinji is absorbed into EVA-01 and apparently all that's left from him is his plugsuit, which a very shaken Misato holds in her arms as she cries... and then 01 "spits out" a naked and unconscious Shinji. Fridge Logic hits when you recall that, right before 01 "took him in", Shinji was in his school uniform and didn't change into his plugsuit. Blooper, anyone?
Godannar also has the pilots commando when in their spandex piloting outfits. Confirmed in the last few episodes.
In Bubblegum Crisis: Tokyo 2040, the Knights Saber are at first commando in their plug suits. Later, they don't even get plugsuits and are naked under their upgraded power armor (which is now transparent in places). Lampshaded by Sylia when she tells Mackie that "he's in the girls' changing room" when they're discussing it, and a totally flustered Mackie runs away all red-faced.
Great Teacher Onizuka: At one point, Fuyutsuki's panties are stolen by three students, who then spread the word that she isn't wearing underwear.
At least one of Tao Ren's outfits in Shaman King would imply this, as the placement of a set of holes in the sides of his pants would normally reveal SOME form of underwear.
Female fans of Raideen like to debate whether Demon Prince Sharkin is going freebird under his very short, divided leather kilt. When gaps appear between the leather strips, you can tell he's definitely not wearing boxer shorts.
Yamada does this on purpose in an early episode of B Gata H Kei. Then she asks her totally not boyfriend Kosuda if he likes girls who go around without panties, but runs away before he can answer. Then at the end, he confronts her, slamming open the door and demanding to know the meaning behind the question... and the wind from the door blows up her skirt, and suddenly everything makes sense.
The Fanservice(ier) episode of Strike Witches has one character with missing panties turn into a Panty Thief. It cascades into people stealing the Panties of another character and in the end leaves multiple characters running around like this with lots and lots of Censor Steam included.
A chapter of Nana to Kaoru has Kaoru making Nana walk around the park without any underwear on. He has to jump through hoops making sure nobody encounters her while she's doing this.
The Omake side story of Hatsukoi Limited is about Andou Soako going through an entire (school) day without her undergarments, and trying to keep anyone from finding out.
In a post-chapter omake strip in Rosario To Vampire, Cat Girl teacher Shizuka is asked what her bra size is. She replies that she doesn't wear one. Which become increasingly evident in later chapters.
Arcade Gamer Fubuki. Fubuki had to go through this trope when her panties were stolen in episode two.
Teenage hit-woman Chinatsu from Jormungand never wears panties to a fight, which comes as a shock to most of the rival characters who often don't notice until they're in the middle of a pitched gun battle. She does, however, have a good excuse for it...
Chinatsu: The first job I ever did with Master, the target's house was on the far side of a river. Skulking around in wet undies felt gross. So I snuck away and took them off. I hit everything I aimed at that day. I even shot better than Master did. He complimented me for it. Koko Hekmatyar:(snicker) Y-you're a better shot without underwear? (snort) Chinatsu: That's right. Koko Hekmatyar: Bwa ha ha! That's a great story!
Nowa in Queen's Blade doesn't wear underwear. She lives with elves, who don't do much better - their usual underwear is a pair of crossed leaves. Echidna, meanwhile, only wears a snake along her lower body - and when her lower half's off-camera, she likes to wear it on her shoulders instead...
Aira:(holding a scythe to Nowa's throat) You're such a wild girl... you're not even wearing underwear. Leina: S-She doesn't?!? Nanael: Elves are really nasty bitches, too...
In Baccano!! several of the female characters wear pretty low-cut clothing (for the standards of the time), and almost none of them seem to have anything on underneath.
Merle in Escaflowne. Then again, she is a Cat Girl, and with that tail of hers it'd be hard to put on ANY kind of panties...
Ooga, one of the Stalker Trio in Mitsudomoe gets so upset at the object of her affections apparently liking panties more than anything she immediately takes hers off, kicks them into the stratosphere, and swears to never wear them again.
Run in A Channel discovers she accidentally forgot to put socks on both feet, while bending down to take the one sock off, Tooru, standing behind her, discovers Run forgot something else too.
In a Lupin III (Red Jacket) episode named "Albatross: Wings of Death", the villains strip Fujiko to find what she stole. They don't find it, but have no reason to allow her to dress, either. She spends the majority of the episode without underwear, or much of anything on, really. Somewhat odd in that this is one of the two second series episodes directed by Hayao Miyazaki!
Mayumi in SHUFFLE! found out the hard way that flinging her clothes where she can't find them is a bad idea, especially while changing into a maid uniform. She only got her panties back later that evening. In the anime, the situation gets even worse thanks to a gust of wind.
Chii in Chobits is naked when she's first picked up by Hideki. He gives her his own clothing immediately and is given 'hand me downs' from Miss Hibeya but she's definitely lacking underwear. Buying her some is the plot of an entire episode. The fact that she has no clue what a bra is is brought up later. In the manga when she gives Yumi her work uniform she's noticeably topless. This was Bowdlerised in the anime to where she's finally wearing a bra.
While excised from the anime for obvious reasons, Rider from Fate/Zero was noted in the Light Novels to have a habit of prancing around the house while wearing neither pants nor underwear.
In the first episode of Tonari no Kaibutsu-kun, Haru drops his pants in front of his class and it is shown he wasn't wearing underwear.
Nanami forgets to bring her underwear to the pool in Episode 8 of Sakurasou no Pet na Kanojo. Misaki makes fun of her for it at the end of the episode when they're back at Sakura Hall.
In Panty & Stocking with Garterbelt, Panty Anarchy's main power is that she can turn any underwear into a gun and back. Since she tends to use her own panties for this, she goes commando in battle. Her Evil Counterpart Scanty Daemon has a similar ability and does the same thing. Panty occasionally borrows Stocking's panties so she can go Guns Akimbo.
A very rare example that is Played for Drama in Koi To Senkyo To Chocolate: poor Isara has her underwear violently removed in an empty lot and thrown to the garbage by a trio of bullies (all female, thankfully), and has to go about for the rest of her day (which lasts, mind you, until way after midnight, since she has to work so many jobs to keep feeding her family) without any. She is shown to be exactly as miserable as any real person would be in the situation.
It is greatly played for Fanservice when she is turned into a child by some weird magic during the Sun Village arc. Her skirt, armor and boots become too big for her and fall off, though her shirt doesn't fall off but is now big enough to act like a dress. When she is turned back, it becomes obvious that she didn't wear panties under her skirt, and with her skirt now being too short to cover her lower body, she fights completely bottomless for a while and isn't even especially ashamed about it.
Played for laughs in Abenobashi Mahou Shoutengai: Arumi's panties are stolen, and then she's subjected to just about every suggestive trope in Humongous Mecha anime, from a skimpy minidress to a giant robot with a suggestive piloting position. She's mortified but her companion Sasshi never notices, as he's too busy with the rest of the Humongous Mecha anime tropes.
Not played for either humor or fanservice in Ano Natsu De Matteru: Mio has a habit of occasionally forgetting her underwear due to being raised as a nudist, despite also being a Shrinking Violet.
In the 25th issue of Thunderbolts the team has to deal with a base filled with 25 supervillains. To be able to move around more freely, they ambush a small group, including female villain Joystick, and steal their costumes, leaving the stripped villains lying in a heap. One of the 'Bolts comments◊ that when she wakes up, Joystick will probably wish she was the sort of person who wore underwear.
The main character of Empowered discovered early in her career that if she wears underwear under her supersuit, she gets epic visible pantyline. Therefore she must go commando. This makes it extra unfortunate that her suit is so easily torn.
The bookends of every edition lampshade this by pointing out the "skintight" outfit does not show cameltoe, and some flashbacks show Emp's pantylines as a means to illustrate how long ago the scene occurred.
Her friend Ninjette does not appear to bother with (or have room for) panties beneath her bootyshorts either. She does not wear bras for that matter, but the latter is justified by her not having anything to put in them.
Gemini Storm: Not one of Elizabeth's outfits suggests she ever wears a bra.
In one of the early issues of The New Avengers, the team is captured and they are all stripped of the costumes. Spider-Man lets out that he doesn't wear underwear because it chafes him.
In a Axis Powers Hetalia doujinshii, Japan dolls up England in a yukata for a "date" with America. America soon lampshades the trope as they walk off together, and then one thing leads to another...
In Harry Potter and the Cracked Reservoir, after Harry starts dating Ginny, each of her brothers plays a prank on him as part of initiation into the family. One of the pranks was enchanting all of his underwear to freeze whenever he thought of his girlfriend. Harry uses the obvious solution, with only Ginny actually told how come he can stand it when she sits in his lap.
Cale in Titan A.E.: after briefly appearing naked, he puts on pants but not underwear.
Happens to Fievel twice in An American Tail, who for some reason actually does not wear underwear despite wearing clothing like all the other mice in the film. However, he does appear naked occasionally.
At the very beginning of the song "Honor To Us All" from Mulan, during the scene where Mulan is forced to remove her green dress and then pushed into a washtub (seen in silhouette behind a canvas, naturally), she clearly isn't wearing anything underneath.
The men in Brave, judging from the scene where they used their kilts to make a rope ladder.
In the Wizards of Waverly Place movie, when packing, Max takes the boxers out of his luggage and proclaims "Who needs underwear?" Presumably, he is going commando for the remainder of the movie.
Happens to Jessica Rabbit from Who Framed Roger Rabbit in an infamous scene where she is shown being tossed out of a car.
In The Covenant, some of the characters make a bet as to what kind of underwear a waitress is wearing. The one who bet "going commando" won.
Casino: 1995 epic crime drama. The senator's hooker, as we find out when we watch her slip out of her gown in the senator's hotel room.
In Salt, Evelyn takes off her black panties and uses them to obscure from surveillance the fact that she's MacGyvering a missile launcher out of cleaning materials and a fire extinguisher ("Get your panties off the camera!") She then climbs up the side of a building and edges along the brickwork without having had the opportunity to put on a new pair.
In Cutting Class (1989), one cheerleader named Colleen (portrayed by Brenda James) removes her yellow-and-black-striped panties before she and Paula leave the locker room, and go on the court to cheer on their team with the other cheerleaders. She does this as a joke and puts on a hot show, flashing her nude rear end and mooning the spectators.
Madonna (Gloria Tatlock) in 1986's Shanghai Surprise. During the scenes in which she and Sean Penn (Glendon Wasey) are riding on separate rickshaws and next to each other and as she reaches towards him, a gust of wind blows her blue skirt back and she's spread eagle, wearing nothing underneath.
In the erotic thriller, Desire (1993), one of the characters can smell that the main character isn’t wearing underwear.
Played for laughs in Couples Retreat, when the characters are told to take off their outer clothing as a therapy exercise and one character admits he isn't wearing any underwear and unsuccessfully tries to refuse.
The cheerleader Juicy Dorfman (Hayley Ladner) from 1988's Johnny Be Good. She's asked to remove her yellow panties so she can flash the opposing football team as a distraction. Though technically it appears she's actually wearing either flesh-colored or transparent undies.
In Thunderball, when James Bond seduces a nurse, she drops her uniform and she's not wearing anything underneath.
In Aquamarine, when the mermaid becomes human, she's naked. Claire and Hailey loan her sandals and an over-sized shirt that she uses as a dress, but no bra or panties.
In The Amazing Spider-Man, Andrew Garfield admitted that he had to go commando while wearing the costume. Although a shot early on in the movie when Flash is beating him up shows that this only applies when he's in costume.
In Easy A, when Olive fakes sex with Brandon, she gives him her panties and presumably spends the rest of the party in her short dress without any.
It's implied that she leaves shortly after.
In Hansel And Gretel Witch Hunters, Mina strips out of her dress and reveals that she's totally nude underneath before entering the pond. Hansel doesn't wait to be asked a second time to join her for a Two-Person Pool Party. No wonder the simple townsfolk thought her a witch.
Implied: In the adaptation of Carrie Fisher's book "Postcards From The Edge," Suzanne Vale (Meryl Streep) rails on her mother Doris Mann (Shirley MacLaine) for lifting her skirt up at Suzanne's get-together. Doris states she twirled it up, and Suzanne points out that Doris wasn't wearing underwear.
Implied in Machete. After April and June Booth wake up naked after having been drugged and kidnapped by Machete, April finds a nun's habit and puts it on.
In Paper Towns, when four of the characters set off on an impromptu road trip, two of them are literally wearing nothing but their graduation gowns.
Night Huntress has the sequence in the first book in which Bones tells Cat that she will be more effective bait by not wearing undergarments with her slut disguises. Later, it is revealed to be a personal fetish of Bones' and he just told Cat to do so to mess with her.
Earlier in Storm Front Susan, under the influence of a love potion, informs Harry that she isn't wearing any panties under her little black dress. While he is naked and wet from the shower and trying to keep them both inside a magic circle that is the only thing protecting them from an attacking demon.
In Succubus Night, part of the Georgina Kincaid series, the protagonist, a shapeshiftingSuccubus, teases her human boyfriend Seth Mortensen by implying she is going commando. Seth can't help but asking several times in the afternoon if it's true. Eventually, Georgina reveals she is wearing panties... only to immediately make them disappear thanks to her shapeshifting and tell him she doesn't wear them anymore.
In John Scalzi's short story After the Coup, Harry (a soldier/engineer) is required by his superiors to participate in a wrestling match. It turns out to be in the nude. The Deputy Ambassador makes a disturbing discovery while Harry is undressing.
Schmidt: (horrified) You went commando to a diplomatic function?
Harry: Yes, Hart, I went commando to a diplomatic function. And now, as you can see, I'm going Spartan. Focus a little.
There's a scene in A Brother's Price where Jerin is sans pants or undergarments and just in a nightshirt, which is how he's dressed when he meets the Princess Ren, who is similarly clad. Later in the book he's scandalized to find that he is expected to wear tight clothing including a codpiece, which he can't wear anything beneath.
In Caddie Confidential, J.J. James relates an anecdote in which Hal Sutton is about to make a putt when his caddie points out a young lady on the slope of the green directly at the end of his line of sight, who happens to be sitting cross-legged and wearing a short skirt with nothing underneath. Apparently Hal 3-putted.
In The Adventures of Captain Underpants, the Captain slings his own underwear onto Dr. Diaper's head. Captain Underpants later appears wearing a barrel.
Ross was trying to get everyone ready for an important (black tie) work event he needs to be at. It's almost a disaster especially with Ross's loss of patience over Rachel's inability to decide what to wear. At the very end of the episode, Rachel finally chooses a skintight dress and, as a form of titillation, she tells Ross she's going commando just as she walks out the door.
Phoebe dated a guy who went in shorts, but no underwear, causing the other guys to recoil in horror every time he sits down. He sits down and puts his foot on the table. Meaning his things are in clear view of pretty much everyone in front of him.
Gunther: Hey buddy, this is a family place. Put the mouse back in the house.
Chandler dated once a woman (played by Julia Roberts) who suggested that he wore her underwear instead of his. It was in-universe Fetish Fuel. It is hinted that she went commando during the dinner date. It was actually a plot to humiliate him.
On an episode of Cheers Frasier agrees to wear a clown outfit for a birthday party as a favor to Rebecca. The outfit includes oversized pants rigged to drop when the handkerchief in the pocket is pulled. Naturally, this is the same day his wife Lilith buys him a pair of European briefs so uncomfortable that he takes them off in the middle of the day.
I think I've paid more than my share. I'm just a poor girl, but you don't care. Hey, I'm not wearing underwear!
Angel. As part of his Dating Catwoman relationship with evil lawyer Lilah Morgan, Wesley talks her into taking off her panties over the phone. During a board meeting.
Puck from Glee loves the days when he goes commando.
There's a children's television program in Japan where school children go to school without underwear while being accompanied by a camera team.
In an episode of Airwolf, in a mission involving dressing in military attire, the woman providing the clothes to Stringfellow Hawke detailed the clothes provided, including the underwear. Hawke was very prompt to clarify that he never used any.
In The Two Ronnies serial "Death Can Be Fatal", the two detectives are searching for an item of female underwear on which the vital clue is written. Ronnie Barker's character gets to investigate the hotel's receptionist — who, as he discovers, "just plays it cool."
There was an ep of Gilmore Girls where Lori admits to Rori she's not wearing any undies her skirt because the laundry was not caught up, and comments that it feels kind of nice. Rory rolls her eyes and makes a snarky comment about her mother as a role model.
This is one of two oft-cited reasons why Catherine Bach's Daisy Duke costume incorporated Tights Under Shorts (the other, more well-known reason had to do with network censorship issues).
"Shitagi Nashi ...", the title of the first-season finale of Don't Trust the B---- In Apartment 23, is the Japanese title of an in-universe comic book series "Tall Slut No Panties" based in Chloe's exploits.
Non-fiction example: in the documentary series Harlots, Housewives and Heroines about women in the 17th century, presenter Dr Lucy Worsley talks about the replica dress she's wearing, raising three layers of fabric to reveal the top of stockings that end just above the knee, then mentions that knickers haven't been invented yet and gives an Aside Glance to camera with a particularly cheeky "oh yes" expression.
Jane Curtin once told viewers she wasn't wearing underwear while doing a Weekend Update segment on SNL.
Unnatural History's camera was careful to watch Henry's backside after his predilection for doing this was revealed.
The Mystery Science Theater 3000 episode "The Castle of Fu Manchu" starts with the Satellite of Love March, where Joel and the Bots gleefully exclaim, "We don't care, don't despair, we're not wearing our underwear!"
At the AFI Lifetime Achievement tribute to Sean Connery, Mike Myers appears in full Scottish kilt. His first line (a very old Scottish joke) alludes to this trope;
"Someone asked me, is anything worn under that kilt? No, nothing's worn. Everything is in perfect working order."
Game of Thrones. Theon Greyjoy pays whore Roz for one last look at what's under her skirt as she leaves Winterfell for more profitable pastures. As per the medieval period, she doesn't have underwear (although 'smallclothes' are mentioned as being worn in the books, at least by the nobility).
Mike And Molly: In one episode Joyce is wearing a Little Black Dress to go out to dinner with an ex-boyfriend of hers. Vince says that he doesn't want her coming home with her panties in her purse. Joyce tells him not to be stupid, as she never wears panties with this dress.
Meg White seems to like drumming without a bra. We don't mind, either.
The song "Go Commando" by Morning Sidekick is about a woman doing this.
Miss Kitty panicked when she was entered into an Evening Gown match - the stipulation of which states that the loser is the one who has her dress ripped off. Why? Because she didn't wear underwear.
Chyna: Well you'll just have to win then, won't you?
The song "I'm Not Wearing Any Underwear Today" from Avenue Q.
Blazblue. Noel Vermillion was suspected by fans for a long time, but this was disproven by EXTEND. Platinum, however...well, just look at the Continuum Shift 2 OP video and paying close attention to the frames between 1:24 and 1:25.
In Destroy All Humans! mind-reading rednecks of both genders can reveal they are going commando. The same thing applies to senior military personnel much later in the game, even General Armquist.
Male example: A common joke about two Nintendo heroes, whereas Link and Marth are claimed to be Badasses because they enter the battlefield without their pants on. The images in the earlier games did make them look that way...
In Leisure Suit Larry III, several puzzles in Patti's section of the game require removing articles of her clothing. Her panties are the first to go.
The limited-edition figurine of Mushihime Sama protagonist Reco lacks panties under its skirt. Presumably because in the figurine, Reco is sitting on a stump, and you'd have to go out of your way to detach her from the stump. This was later brought up in a Famitsu interview with director Tsuneki Ikeda and producer Makoto Asada, where Ikeda confirmed that she canonically does not wear any underpants. Hilariously, Asada's only thought on the matter was to ask Ikeda if that means she can pee standing up.
Evoked in Persona 3, in a quite funny form. Cute kid Ken asks the main character if girls were Going Commando in the New year festival, and then he also asks what Going Commando means (he overhead it from Junpei, who also comments this). Note that this is because the girls are all wearing kimonos at the festival and there's a sort of urban legend that women who wear kimonos don't wear underwear. If you play through the female protagonist's story in the portable version, Ken asks "aren't you girls cold?" with equally hilarious results.
... Worth noting: Those two breeds have a 50% and 25% chance respectively of being male.
Theoretically, given that of all the characters shown undressed during the sex scenes in the Mass Effect trilogy everyone who is shown wearing underwear is human, we have no evidence anyone else wears underwear at all. It could be merely a human invention.
In Dm C Devil May Cry, Dante gets dressed (in midair, in slow motion) and clearly does not put on underwear.
The creator of Hatoful Boyfriend confirmed that Ryouta doesn't wear underwear... or anything else, since like most of the cast he's a pigeon. Unless he's wearing women's clothing. The sequel features a Q and A where one of the questions sent in is "What color are your panties when you're in human form?", and Nanaki confesses that he forgot to put his on, while Okosan says he needs no panties and Miru and Kaku are always completely naked. ...of course, those last three don't have human forms.
Misfile. Ash gets so irritated by a thong that she switches to this option.
This becomes an issue a few strips later when she falls down.
Sam the scientist from The Strangerhood was forced to do this for three months after Sam the abductee stole all his underwear.
In the Homestar Runner short "New Boots", Strong Bad complains that The Cheat animated him with underwear showing, saying "Everybody knows I don't wear underwears!" though this claim has been contradicted on multiple occasions since then.
Para: Against our Gate Guardian, you stand no chance.
Dox: I'm not wearing any underpants.
Para: Is that true brother, or are you just rhyming?
Dox: I didn't want to throw off our timing. [Beat.] But it is true.
In Season 3 of The Guild, when the Axis of Anarchy first appear, Clara is very interested in knowing whether Fawkes is naked under his utilikilt. He takes great pleasure in smugly informing her that he is.
In one episode of Quack Pack ("Koi Story"), Daisy is revealed not to be wearing any unmentionables under her mini skirt, when an earthquake causes her to bounce and lose balance before getting into spread eagle position in front of the viewers. When Gil presses a button on a remote that causes a large, rocky wall to split and reveal a giant fishbowl.
In The Simpsons episode "Sideshow Bob's Last Gleaming", Bart is "going commando" when he and Lisa get trapped in the airforce base.
Bart: Ahhh! Free and easy, Lis'! There's nothing like an unfurnished basement for pure comfort.
Naturally, Groundskeeper Willie often goes commando, as evidenced when he parodies the Basic Instinct interrogation scene in "Who Shot Mr. Burns? Part 2" (much to the disgust of Chief Wiggum).
On the opposite end of the spectrum, the boy in The Snowman changes out of his pajamas directly into his clothes without even a pair of Long Johns underneath. Most likely done for humorous effect.
One episode of Total Drama World Tour entitled "The Am-AH-Zon Race" reveals that Cody is under the impression that nobody wears underwear in the Amazon and, therefore, he decides to go without. Gwen, upon finding this out through the use of X-Ray glasses, is quite disturbed...
Cody:(blushing) Heh-heh... who wears undies in the Amazon? Gwen:(in confessional) Everyone! Everyone wears undies in the Amazon!
In The Venture Bros. episode "Ice Station — Impossible!", Rusty confesses that he is not wearing underwear. When his Impossible jumpsuit shatters, this is proven true.
In the Regular Show episode "Diary", one of Mordecai's secrets is this trope. Made funnier by the fact that he doesn't actually wear clothes.
Mordecai:' "I like going commando!" beat. "A LOT!"
Historically, Regency men went like this all the time (as boxers and briefs have not yet been invented). For comfort and to prevent the embarrassment of urine leaking and ruining their trousers, they would tuck the lower parts of their shirt between their legs, which would be secured by the tight pants.
According to his autobiography Ain't Got Time to Bleed, Jesse Ventura was afraid that someone who was in his Vietnam War era SEAL unit would show up to shout "skivvie check!" at his swearing in as the governor of Minnesota. When he was serving, when that call was made others were obligated to stand up and drop their pants, to show they were sans underwear.
It's sometimes necessary for soldiers, because not having the chance to dry off downstairs can give you the mother of all jock itch.
Britney Spears was caught more than once going like this by the press.
A more graphic case would be Lindsay Lohan; pretty much everybody now knows exactly what she looks like "down there".
Underwear didn't become common in most of Europe until after the Black Plague.
For women it was much later than that. Even in the 18th century female undergarments were (perhaps ironically in hindsight) mainly associated with prostitution.
Some women do this while wearing pants to avoid VPL (Visible Panty Line).
Liv Tyler while playing Arwen often had to go commando in order to wear some of the elvish costumes.
Jeff Foxworthy did a stand up routine about this trope and gender roles. When a woman mentions that she's not wearing underwear, it's a turn on for men. When a man mentions not wearing underwear, the reaction from women is quite different.
"Good Lord, I'm going to have to wash those pants twice!"
Taiwanese superstar, Jay Chou cheerfully admits to this. This fact is famous in Asian showbiz.