* In episode 7 of the anime ''Anime/HanasakuIroha'', Ohana hums the opening theme in the bath.
* In the original Japanese version of the first season of ''Anime/SailorMoon'', its theme song, "Moonlight Densetsu", is apparently a current hit. It is sung several times by different characters, including once as a duet in a talent show. (It should probably be noted that the "fighting evil by moonlight" lyrics were created for the North American dub; the original is actually about finding one's "miracle romance".) Interestingly, a slow version of the same tune is played by the star-shaped locket in the first season -- this locket is also present in a flashback to the Moon Kingdom, which existed in the distant past. Perhaps the song is older than it seems...
* Although it's not the show's theme tune, the anime ''LightNovel/FullMetalPanic!'' regularly uses a variation of the theme song from ''Series/TheATeam'' as background music. In the follow-up series ''Anime/FullMetalPanicFumoffu'', the song is also used as the main character's cellphone ringtone, and one other character remarks how it sounds "just like the theme song of one of those old American TV series".
* In the 2005 series of the {{anime}} ''Manga/AhMyGoddess'', Belldandy and Holy Bell sing a haunting rendition of the theme song, ''Open Your Mind'', as part of a magic spell. In the second season she sings it again during a talent contest with Sayoko, who sings the first season ending theme.
* Similarly, during the FestivalEpisode of ''LoveHina'', Seta asks Haruka (voiced by MegumiHayashibara, who recorded the theme) to sing for him "just like she used to." She then begins singing a slow, almost melancholy, version of the very hyper theme song. Most of the other Hinata girls scattered throughout the festival each join in, until there is a chorus of voices singing on the final line.
* Characters in ''MartianSuccessorNadesico'' frequently sing snatches of the [[AnimeThemeSong opening theme]], most often just the title line "You Get to Burning" -- and usually not very well. At one point Erina even chastises Yurika for messing up the lyrics.
** And in the "Idol Singer" episode, Yurika sings an expanded version of the ending theme.
** In the Christmas episode, Seiya makes up Christmas-related lyrics to sing to the tune of the opening theme.
* ''MagicalGirlLyricalNanoha'' uses the [[AnimeThemeSong theme song]] as a cellphone ringtone.
* ''Manga/AzumangaDaioh'' does the same thing with a character's ImageSong.
** Tomo has her ImageSong as a cellphone ringtone.
** Osaka and Sakaki sang their [[ImageSong image songs]] at the karaoke. Yomi does the same and [[RuleOfFunny epically fails]]. As if Creator/RieTanaka couldn't sing...
*** More on Sakaki, her ImageSong appears again in the radio show that both Tomo and Yomi were listening to, only it's listed as being sung by YuuAsakawa, who is actually Sakaki's [[PigeonholedVoiceActor seiyuu]].
* ''TokyoMewMew'' also has one of its theme songs as a cell phone ring, and one episode involves two characters bonding over the song and making plans to go to the artist's concert.
* Hazumi and Hatsumi listen to the AnimeThemeSong to ''YamiToBoushiToHonNoTabibito'' on a train in episode 7.
* ''Anime/AbenobashiMahouShoutengai'': In a world that may or may not be the original one from which they come, Sasshi and Arumi stand in the shopping arcade proper and look around while the closing theme of the show plays, muzak-style, over the PA system.
* In ''KeroroGunsou'', while doing chores around the house, Sgt. Keroro sometimes sings his own version of the show's closing theme.
** Another episode had Sumomo singing a few bars of the show's theme.
** Another one had the first ending as Fuyuki's ringtone.
** And ''another'' one had the first season's summer-only Dance Festival ending used for a dance rehearsal, about two years after the fact.
** Even the manga gets into the act; the first chapter of volume 19 features Keroro singing one of the closing themes from the anime at a karaoke club.
* In an episode of ''PrincessPrincess'', the "princesses" and student council go for karaoke to train for the school festival. The StudentCouncilPresident begins to sing the opening AnimeThemeSong in one room, whereupon the "princesses" retreat to a different room by themselves... and sing the ending theme. Then, when the actual concert comes, they sing the theme to ''CuteyHoney''.
* In ''{{Nana}}'', the Black Stones' first hit song is the OP for the series, and a hit single from their chief rival band is the series ED. Both songs show up several times in the show itself.
* In ''OuranHighSchoolHostClub'', Kaoru and Hikaru have the series ED as one of the ring tones on their cell phones.
* A quieter, softer version of the theme for ''WORKING!!'' plays as the restaurant's background music.
* In an episode of ''Rockman EXE'' (''Anime/MegaManNTWarrior'' outside Japan), the protagonist's mother is humming the opening notes (from when they start singing) of the theme song.
** The sequel series, ''[[MegaManStarForce Ryuusei no Rockman]]'', reuses the opening as the first song a popstar composes on her own after angsting about only singing what's given to her. In the first episode she sings it in, she uses it to ''distract TheDragon Gemini Spark from a battle''. Yes, he/they (don't ask) stand there and stare at her for the entire ninety seconds the song goes on. So does Rockman, actually, not attacking as per the diversion she intended the song for until the last couple seconds of it.
*** Also done in ''[[MegaManStarForce Ryuusei no RockMan Tribe]]''. The song Misora sings at the concert in the last episode is the theme song, "Kizuna Wave." The animators even used footage from the opening (although that may have because the ending was rushed to completion).
** In one episode of ''Rockman EXE Axess'' Netto hums the ending theme of that series while he's in the shower.
* The opening of the anime series ''{{Gankutsuou}}'' (''We Were Lovers'' by Jean-Jacques Burnel) appears in-show as the song one of the characters composes and plays on the piano in several occasions.
* ''Re:CutieHoney'' plays with this by having a villain sing the theme song... but replacing the lyrics about how beautiful Cutie Honey is with how much she ''hates'' Cutie Honey. She even gets the ''{{mooks}}'' into the action.
* The ''Anime/PrettyCure'' franchise does this way too many times:
** In one of the later episodes of ''Anime/FutariWaPrettyCure'', the choir club has to find a song to sing... and they pick the show's ending theme.
** And they even dubbed the song in the English Dub of Pretty Cure instead of replacing it, although the ending theme was an instrumental of "Together We Are Pretty Cure", the dub's opening theme.
** The same theme (Get You! Love Love?) would occasionally be hummed by a recurring character, even once after the show became ''Futari Wa Pretty Cure Max Heart'' and the ending theme was replaced with a new one, named [=MuriMuri=]? Ariai! [=INJanai=]!?
** In episode 12 of Max Heart, Honoka, Hikari, and Akane sing the the first verse of the show's ending theme, Murimuri!? Ariari!! IN jana~i?! (Impossible!? Possible!! Isn't it?), while driving to the Nadesico Ranch Festival.
** In ''[[Anime/YesPrettyCure5 Yes! Pretty Cure 5 GoGo]]'', the theme song plays over the attack sequence.
** ''Anime/FreshPrettyCure'''s first ending is apparently part of Trinity's song list (played in the first episode). The second ending is played during a dance contest in the final episode.
** The orchestral version of You Make Me Happy! played during the episode of [[FreshPrettyCure the next season]] when [[spoiler: Eas dies]].
** ''Anime/HeartcatchPrettyCure'' gets into the act in episode 41, using both the opening and second ending themes for the respective parts of a puppet show.
* In SmilePrettyCure, a instrumental, slow version of Yay! Yay! Yay! is background music.
* ''Manga/ElfenLied'''s theme, "Lilium," was frequently used within the show -- Kouta had a music box which played the tune, and was playing it when he and Lucy met as children. In the present, the theme was used to allude to their former relationship, the memories of which Kouta had suppressed after Lucy killed his family. For instance, it made Nyuu very upset, even though she didn't know why, and even caused her to revert to Lucy.
* Lucia's music box in ''MermaidMelodyPichiPichiPitch'' plays the show's first ending theme, and sometimes the episode titles and important lines are actually song titles (usually "Yume no sono saki e"). Being a series that incorporates music all through, there are too many instances of characters singing [[ImageSong their own songs]] to list.
* ''Manga/DeathNote'' has Nightmare's "Alumina", the first ending tune, as the ringtone on Matsuda's mobile phone, and the first opening tune on Misa's.
** Also "Alumina" can be heard on Misa's laptop in episode 13. Still it goes largely unnoticed by most fans.
* Episode ten of ''Anime/ParanoiaAgent'', in which a frantic victim accidentally turns on his car radio and the show's opening theme song plays.
* ''Anime/LupinIII'' has several examples of Lupin's "ya-tah-ta-''taa''" theme song appearing during the story itself.
** ''Anime/LupinIIICrisisInTokyo'' features Lupin whistling it.
** In the TV special ''Anime/LupinIIIStolenLupin'', Lupin's ringtone played the theme song.
** Lupin is also whistling the theme tune while crossing the desert in ''Anime/LupinIIISweetLostNight''
%%
%% Which series? This isn't a helpful example.
%% ** Anime/LupinIIIRedJacket?? Fujiko humming it while driving a truck in the series proper.
%%
* One dub episode of ''Anime/YuGiOhGX'' has Jaden singing part of the theme song.
** Another dub episode has Fubuki/Atticus singing (badly) a {{Parody}} version of the theme song. "Rock on! Get your rock on! Everybody rock now!"
** In the original version of [[Anime/YuGiOh the original series]], it happens too, with Anzu's ringtone being the second season opening song.
** The ''Anime/YuGiOh5Ds'' dub does this twice. At one point, the hyperactive CloudCuckoolander scientist is caught singing the theme. Yusei also had it playing on a music player in one episode, while fixing his [[CoolBike Duel Runner]].
* The ending theme of ''Manga/RurouniKenshin'', sung by the voice actor of Sanosuke, was discontinued; in the next episode, Sanosuke is walking down a street and singing it.
* In the ''WebVideo/{{DNA}}'' {{OVA}}, Karin Aoi and Junta's mother sing karaoke, performing the series's closing and opening themes respectively.
* ''LightNovel/HaruhiSuzumiya'':
** In episode 9/14 ("Someday in the Rain"; see AnachronicOrder), Haruhi sings a snippet of the show's ending theme while undressing Mikuru. Don't ask.
** And in another example, Kyon's little sister hums a bit of the ending theme while stealing Kyon's scissors.
** In ''Manga/HaruhiChan'' episode 4, Mikuru hums some of the aforementioned ending theme while getting her maid clothes.
* ''Manga/LuckyStar'''s Konata uses the ending theme from another Kyoto Animation show, ''[[LightNovel/HaruhiSuzumiya The Melancholy of Haruhi Suzumiya]]'', as her ringtone. The song also shows up in a few other places, including an arcade rhythm game.
** She also hums the opening theme for ''[[LightNovel/HaruhiSuzumiya The Melancholy of Haruhi Suzumiya]]'' while playing her BrandX {{MMORPG}}, replacing certain lines with MMORPG-specific phrases.
** One episode has a scene where Konata and her friends attend a concert featuring an ImageSong from ''[[LightNovel/HaruhiSuzumiya The Melancholy of Haruhi Suzumiya]]''.
*** This is a real world concert ''Suzumiya Haruhi no Gekisō'' that the characters 'attended'. The 'person' singing on stage is Aya Hirano, credited as such (she is also the VA of Konata and Haruhi) and is a fairly good likeness of the actress.
** The ending themes for ''Lucky Star'' up to episode twelve are often themes to other (non-KyotoAnimation) series, anime or otherwise. The others are general popular tunes.
** And yes, ''Lucky Star'''s own theme makes an appearance, hummed by one of the girls in episode 6.
*** And in episode 24, when the DancingTheme is animated in full. (Well, full shortened version, anyway.) In the same episode, Minoru is interrupted by his ringtone, which is his own version of "Koi no Mikuru Densetsu"(one of the endings).
* Mitsuki's idol songs from ''Anime/FullMoonOSagashite'' are all used as ending themes throughout the series.
* ''Manga/HayateTheCombatButler'' not only has the characters doing karaoke with their [[ImageSong Image Songs]] and the show's ThemeTune in one episode, the ending segment of the show is a clear advertisement for said songs. With NoFourthWall, this is commented on.
* The Arcus Prima in ''{{Simoun}}'' has a phonograph-like machine which is often heard playing background music from elsewhere in the series. It ''almost'' escapes this trope, but it finally plays one of the themes (the end theme) in episode 25.
* In one episode of ''Manga/AiYoriAoshi'', Kaoru of all people sings karaoke to the end theme. A different song (sung by Tina) plays over that episode's credits, perhaps indicating some kind of theme conservation law. Aoi is also humming the opening theme at the beginning of episode 15.
* The vocal version of the aptly named instrumental track "Nagisa" from the ''VisualNovel/{{CLANNAD}}'' visual novel, "Dango Daikazoku", is used as the first ending for the anime series, and is sung in the second episode by Nagisa herself. It is also said to be Nagisa's favorite song. Also, as evidence of how much his girlfriend is rubbing off on him, Tomoya whistles it in the third episode of the After Story. It makes several other appearances throughout the anime, too.
** In TheMovie, Nagisa sings the song and it is also used as background music.
* Used often in Anime/NeonGenesisEvangelion with "Fly Me to the Moon".
** The anime also contains several musics based on the opening theme, "Cruel Angel's Thesis." Also note that in an interesting reversal, the ending theme of the movie ''Death and Rebirth'' ("Thanatos -- If I Can't Be Yours") was based on a music from the original anime.
* The HotSpringsEpisode in ''Maburaho'' has Kuriko listening to the theme song on her portable music device on the train.
* Alicia from ''Manga/{{ARIA}}'' at one time hums the opening tune of the series while lighting some candles in her home.
* Inverted in the second ''Anime/DigimonTamers'' [[TheMovie movie]]. Parasimon forces Ruki's memories of her father to the surface, and of a song she used to sing for him--which just so happens to the movie's ending song. While Ruki's seiyuu recorded the full song (which was later released on CD), the version over the end credits was performed by Creator/AiMaeda, the regular singer for nearly all of the franchise's [[AnimeThemeSong ending songs]]. Later, during her birthday party, Xiaochun and Ruki's mother sing karaoke of the series' opening and first ending, "The Biggest Dreamer" and "My Tomorrow".
** While we're at ''Tamers'', an interesting one: Ritsuko's ringtone is Ravel's ''Boléro''. While technically not originally a ''Digimon'' song, the track was part of ''Anime/DigimonAdventure'''s soundtrack, usually played within the context of the real world.
** In ''Anime/DigimonAdventure'', the song Mimi sang to wake [=TonosamaGekomon=] was the first ending, ''I Wish''. Mimi was also voiced by Ai Maeda, so they just had to use the prerecorded audio until he woke up.
** In ''Anime/DigimonAdventure02'', there are two scenes of Yamato's band playing his [[ImageSong image songs]], "Walk On The Edge" and "The Key to Granting Wishes."
** Also in ''Adventure 02'', Hikari hums "Break Up", the Armor Evolution theme.
** In ''Anime/DigimonXrosWarsTheYoungHuntersLeapingThroughTime'', Nene performs two songs at her concert: "New World", the second opening theme to the preceding ''Anime/DigimonXrosWars'' in which she was a main character, and on two occasions performs snippets of "Stand Up", the current opening theme. Being that the songs' artists, Twill, don't do voice-acting, both songs were covered by Creator/HoukoKuwashima for their use here, just not particularly well...
*** The ''Manga/DigimonXrosWars'' ''manga'' got in on this, with Shoutmon singing the anime's opening theme at the end. [[spoiler:He also sing's ''Adventure's'' opening.]]
* Hideaki Asaba from ''KareKano'' is seen (and heard) listening to the series' opening theme, ''Tenshi no yubikiri'', in one of the later episodes of the anime.
* An early episode of ''UltraManiac'' involves the characters going to a karaoke bar and singing snippets of the opening and ending themes as duets. Singable lyrics were written for the dub. Nina, a transfer from the Magic Kingdom, sings a song from ''{{Doraemon}}'', since it's the only one she knows.
* In one episode of ''The VisionOfEscaflowne'', a character finds and plays a music box. The song it plays is "Yakusoku wa Iranai", the show's opening theme.
* ''KonjikiNoGashBell'' starts playing the first theme almost any time the main characters reveal a new FinishingMove. And dozens of other times as well.
** The first episode with Apollo shows him playing the opening theme for children on a flute-like instrument.
* If you listen closely in episode 27 of ''GetBackers'', "High School Girl vs. Recovery Service," you can hear some random background girls singing the recently replaced [[AnimeThemeSong first opening.]]
* Miya does this in ''KoiKoi7'', but her particular rendition of the show's OP is...[[HollywoodToneDeaf terrible.]]
* ''Anime/DaiGuard'':
** One office worker in can be heard humming the show's opening tune while playing with an action figure of the eponymous robot.
** In one episode Akagi sings part of the Dai-Guard Take Off music when he's teasing Ibuki, but it's only in the dub.
** Ibuki has the main theme in chiptune form as a ringtone.
* Maruko can sometimes be heard humming Odoru Poroponkin (depending on which season you're watching is either the show's opening or ending theme) in ''Chibi Maruko Chan''.
* The Junior Detective League in Manga/DetectiveConan keeps singing openings and endings themes in the series.
* The second season of HidamariSketch ends with the cast singing the first season opening.
* In ''MacrossFrontier'', nearly all {{OpeningTheme}}s and {{EndingTheme}}s (save the first OP) are sung by the in-universe {{IdolSinger}}s. This crosses over into OpeningShoutOut territory [[spoiler: in the final battle]] when sequences from both opening credits are used with parts of the second OP playing in the background.
** Although not quite as blatant, ''MacrossPlus'' evokes this trope with "Voices," the first and last song heard in the OVA, sung by Myung at various points, and used in instrumental form as her {{leitmotif}}.
* In an episode of ''RanmaOneHalf'', some characters perform part of the first season opening song for karaoke.
** One of the opening songs also appears in a TV show that Ranma is watching.
** It goes further than that: in the ChristmasEpisode {{OAV}}, the characters that would compose the [=DoCo=] supergroup (Akane, female Ranma, Kasumi, Nabiki, and Shampoo) perform the "Equal Romance" ending theme for the benefit of their party guests. Additionally, an entire two-part {{OAV}}, ''Nettou Uta Gassen'', consists of the entire cast performing a multitude of songs in-character.
** After a particular [[StatusQuoIsGod denial of a normal body]] for Ranma, he closes the episode in girl form, sadly singing the refrain to that season's end theme: "Don't cry, China Boy..."
** Another instance of this occurs in anime season 3, episode 18. Ling-Ling and Lung-Lung use weaponized music that forces the opponents to dance while they are blasted with fire. The music playing is the first opening theme and it seems that [[TakeOurWordForIt we never hear the music that's actually playing]]. When Ranma defeats Ling-Ling and Lung-Lung, the stereo lands on a tree. The stereo opens and the music immediately stops playing, implying that the music Ling-Ling and Lung-Lung used was the first opening theme after all.
* Similarly, in ''Mezzo DSA'', Mikura brings her karaoke machine on a car ride (to Harada's annoyance) and sings the theme song. This would be fine if she didn't sing it ''all the way through''... '''more than once'''. You'll never see a more obvious "rake scene" in anime.
* In ''{{Gravion}} Zwei'', during a HotSpringsEpisode the [[BridgeBunnies maids]] are without their cool control room during an attack, so Klein Sandman gives them karaoke microphones so they can they sing the SuperRobot CombiningMecha TransformationSequence theme song.
* The bar in Tokyo where Lucy meets Akagi [[spoiler:some time after Saeko's death]] in ''FLAG'' has a lounge singer singing the show's ED song, ''Lights''. The singer herself looks suspiciously like Eri Nobuchika, the real-life singer of the ending theme, and the bar itself is named Lights.
* ''Top wo Nerae!2 {{Diebuster}}'' episode 4 has a moment where Nono hums the beginning of "Active Heart," the opening of ''GunBuster.''
* ''Monster'' uses its theme song as background music at restaurants, dance clubs, and such. The sneaky part is that it's played cabaret-style -- so slow and laid-back that you can easily fail to recognize it.
* ''Anime/HellGirl'' has used at least two of its themes as ringtones. Also noteworthy: [=SNoW=], who sings the OP of seasons one and two, has a cameo on an advertisement at the end of ''Futakomori'''s theme.
* In the first series of ''Manga/DragonBall'' (at least in the French dub, which had a different opening) Goku hums the Japanese theme song before kicking ass.
** Launch briefly does the same during Goku's second fight with Piccolo Daimo.
** In the Ocean Group dub of ''DragonBallZ'', when Bulma, Gohan, and Krillin were on Fake Namek, Bulma started singing the original Funimation intro of ''Dragonball''
* ''{{Tayutama}}'''s ninth episode has a brief KaraokeBox session that has characters singing the anime's opening and ending, as well as the opening of the fandisc of the VisualNovel it was based on.
* ''CromartieHighSchool'' plays with this in Episode 3: 'Hmm hmm hm-hm-hmm hmm-hmm hm-hm-hm-hmmm-hm-hm' [[spoiler:It's "Ningen Nante", another song by the maker of the show's theme. You'd think it was related to the show, but it's actually SubliminalAdvertising.]]
** The show uses three different credits songs, and all of them get a cameo at some point:
*** The first ending credits tune gets played on a cellphone, who is Mechazawa's little brother.
*** When a one-off character listens to his CD-player, you can hear the second tune playing right before it breaks.
*** Kamiyama sings part of the lyrics for the third tune (which appears to be the rock version of the school's AlmaMaterSong) 14 episodes before it gets used.
* Played with in an early episode of ''Anime/{{Pokemon}}'', "Here Comes the Squirtle Squad". Ash is humming along to the BGM, which is not the opening theme to the show, but rather the title screen music from the video game. [[LampshadeHanging Lampshaded]] by the narrator, [[DepartmentOfRedundancyDepartment who brings it to the audience's attention]].
** The Japanese version of the previously-banned-then-not-anymore-and-then-again-yes episode, the BeachEpisode, has Koujiro (James) exclaiming that he and Musashi (Jessie) will "go through the fire and through the water". The sentence is part of the original opening's lyrics.
** Any time Brock has to sing, he will always sing "Takeshi's Paradise" (Takeshi being Brock's name in Japan), one of the end themes in the Johto arc; apparently it's the only song he knows.
** And other OP's and EP's have been used as background music too, but most of the time this is lost in the dubs.
* The first scene of episode 69 of ''ShugoChara'' has Kusukusu humming the show's opening theme.
* In ''Anime/DuelMasters'', after Knight is accosted by a mysterious cloaked servant of the Temple [[spoiler:(who happens to be Mimi)]], he leaves wondering what the other person could possibly be thinking. Her thoughts are revealed afterward. "Who's the kid with the spiky hair? Shobu!"
* The HotSpringsEpisode of ''The Galaxy Railways'' sees a group of BridgeBunnies singing the show's opening theme at a talent competition. They've dragged the main character into singing with them. In ''drag''. His love interest, understandably, responds by [[INeedAFreakingDrink downing a glass of sake.]]
* In an episode of ''Manga/{{Suzuka}}'', a very bored Hatari is left alone in a karaoke parlor and is shown (barely) singing part of the show's opening theme.
* In episode 14 of ''SasamiMagicalGirlsClub'', Itoki sings both the opening theme and the first closing theme at a karaoke parlor. The scene begins with her singing the opening theme, then later in the same scene she starts singing the original ending theme and the screen behind her even shows a glimpse of the original ending credits.
* Taken to ridiculous levels in ''[[HimechanNoRibon Hime-chan No Ribbon]]''. Apparently, "Egao no Genki" (the series' opening) and the band that performs it, SMAP, is extremely popular in Hime-chan's world -- in one episode, Hime-chan pretends to have invited SMAP to a school event to save the drama club's reputation by turning into the band members and walking out on stage one at a time, there was almost a scandal when Hibino was caught hugging Hime-chan disguised as one of the band members, and the song pops up all over the place.
* If you carefully listen to episode 31 of the ''VideoGame/{{Kirby}}'' [[KirbyOfTheStars anime]], Mike Kirby will be singing to the first ending theme of Japanese version, "Kihon wa Maru". Kirby sings it in "Kirbyese" though (his "Poyo" sounds), but if you listen carefully you can hear him say "Kirby" and "Dedede" at the appropriate points in the song[[hottip:*:since names are some of the few things he can usually manage to say]].
** In episode 55, just after the title card, Escargon sings a song about how much he loves ([[HoYay in a platonic way, not like that]]) King Dedede, set to the tune of the first Japanese opening, "Kirby March".
** Two of the various songs that play during battles with the MonsterOfTheWeek contain a remix of part of "Kirby March". Both made it into the game ''Kirby Air Ride'', one as the [[http://www.youtube.com/watch?v=-2uNe2Uub30#t=0m19s Kirby Melee]] music, the other as the [[https://www.youtube.com/watch?v=U-orPpeeocI Checker Knights]] theme. Checker Knights in particular also found its way into ''VideoGame/SuperSmashBros Brawl'', as one of the themes that randomly play on the Halberd stage.
** At the beginning of episode 58, several characters are seen painting graffiti of King Dedede on a wall while singing the second half of "Kihon wa Maru", the lyrics of which which naturally concern how to draw him. A couple lines before the end, which translates to "I promise Dedede will arrive", the king himself chases them away.
* ''Manga/OutlawStar'''s opening theme is played by a gigantic advertising spaceship in the episode "Final Countdown." The first ending theme also appears twice, sung by Melfina.
* In ''YoureUnderArrest'', the episode in which Sena is introduced has the first opening theme, ''100 MPH no Yuuki'', play on the radio.
** Natsumi also sings part of the second opening theme in one episode.
* An episode of ''Manga/BlackJack'' (I'm not sure which one.) had a woman singing the second closing theme song on stage.
* In a episode of ''Manga/BusouRenkin'', Hideyuki Okakura hums the theme song.
* ''Wecomic/AxisPowersHetalia'' is guilty, too. In one episode when all the [[MoeAnthropomorphism countries are in line at the supermarket]] doing something rude, obnoxious, or disruptive... South Italy cuts in line while whistling the main theme.
** In episode 47, Little Italy interrupts Austria's piano recital while singing ''Maru Kaite Chikyuu''. In the middle of it, Italy's voice changes, and Austria not realizes that Italy hit puberty, ''he found out that Italy wasn't female.''
** At the end of ''World Series'' episode 34, Italy hums ''Hatefutte Parade'' while spying until Germany tells him to stop.
* In ''Manga/PeachGirl'', Momo and Sae's ring tone is an instrumental version of the opening theme.
* In (one) BizarroEpisode of ''Anime/ErgoProxy'', Vincent is trapped on a game show, and one question is to name the composer of a song. Then the theme tune plays, and we find out that Vincent guessed correctly. The Fourth Wall was never the same again.
* The protagonist of ''KamikazeKaitouJeanne'' hums her opening on one occasion.
* In the first ''SorcererHunters'' {{OAV}}, Carrot asks "What's up, guys?"...a reference to the opening theme song of the ''Sorcerer Hunters'' TV series.
* In the second season of ''Anime/StrikeWitches'', Shirley hums the first season's ED.
* In one of the early episodes of the dub of the Witchblade anime, a character hums part of the chorus of XTC, the show's first opening.
* In ''VideoGame/{{Touhou}}'': A Summer Day's Dream, Suika hums a snippet of the opening theme as she helps Reimu clean up the shrine.
* In episode 8 of ''{{Slayers}} Evolution-R'', a scene opens up with Gourry humming along to the soundtrack, only to be scolded by Xelgadis.
* At one point, [[Manga/CityHunter Ryo Saeba]] whistles the beginning bars of ''Ai yo Kienaide'', only to be cut off when confronted with a beautiful lady.
* ''Anime/ExcelSaga'' takes this to the next level, with the song being performed by animated representations of the voice actresses who normally sing it, themselves being dressed in the distinctive outfits of the main characters and being derided as knockoffs thereof.
* The English dub of ''BurstAngel'' has the ending theme recited as a poem in one episode.
* In one episode of ''Anime/WindyTales'', Nao sings the ending theme song as part of an audition.
* When the cast of ''YumekuiMerry'' goes to a karaoke bar, we hear someone down the hall performing the show's theme song, and doing a remarkable job of sounding like the original singer.
* ''Anime/PuellaMagiMadokaMagica'': Madoka listens to the OP in a record store during episode one. And, in episode 6, a techno version is played on Kyouko's game of [[VideoGame/DanceDanceRevolution Dog Drug Reinforcement.]]
* ''Anime/NerimaDaikonBrothers'' combines this with WaxingLyrical in one episode: while apologizing to Ichiro, Hideki and Mako quote lines from the opening theme.
* The 2007 ''Tamagotchi'' movie uses the ending theme as Tanpopo's ringtone. This is done twice: at the beginning of the movie, and [[spoiler: at the end of the movie, when the Tamagotchi cast uses the key to send Tanpopo back to the same time she came to the Tamagotchi World]].
* A fairly subtle one in ''Manga/CardcaptorSakura'' has a random woman humming the second season opening as she walks to the mailbox.
* ''GuiltyCrown'' has Inori singing the first ending theme in-series [[spoiler: to combat the effects of the [[TheVirus Apocalypse Virus]] that had been activated by a crystal resonance.]] She also sings "Euterpe," the song that the series began with (but isn't the official opening theme), to herself when she's lonely... and also sings it at the Cultural Festival the high school puts together.
* Rin in ''Kodomo No Jikan'' hums the opening theme, "Rettsu! Ohime-sama Dakko" - basically, "[[GratuitousEnglish Let's]]! Carry me like a princess" - to herself in the bath. An earlier scene plays on the theme's title, where Rin asks her teacher to carry her like a princess.
* In ''MagicalPrincessMinkyMomo'''s second series, the episode "Momo and Momo" has two instances of this. First, the intro to the first series plays when the magical dresser explains the story of the original Minky Momo. Later, the original Momo sings the same song when cleaning a chimney. This happened in another episode involving a "Fenarinarsa satellite", where the original Momo sings it while watching the filming of the satellite before she talks to the other Momo.
* ''{{Franchise/Anpanman}}'' has the theme song, "Anpanman's March", sung by the town's children a few times when they go on class trips. Also, Tendonman and Katsudonman's in-show songs are modified version of their [[ImageSong image songs]], and they sing it every time they're in the show (Kamameshidon's song is completely different from his image song).
* An odd variation: In ''TenchiUniverse'', when Mihoshi and Kiyone go to the karaoke club, it's apparent that they sing the song "Sleeping Beauty on the Balcony", the theme to the special "Space Police Mihoshi's Space Adventure", the special that introduces Kiyone.
** In the manga ''No Need For Tenchi'', one incident has Katsuhito learning that there was a dangerous wolf out there and that the others, who were looking for Sasami, were still out there. He stops when he finds out the next song on the radio is Ai Orikasa's "The Moon Tragedy" (better known here as "The Lonely Moon"), which was the OVA's second ending theme.
* Two episodes of ''Manga/KotouraSan'' include scenes in a karaoke box: episode three has Haruka singing the opening theme, while episode twelve has her singing the ending theme.
* The ''Anime/Patlabor'' OAVs have their own theme song playing on a TV channel as the off-duty crew flip through the channels looking for something to watch. Ohta even says to flip back to it after Asuma goes past it a second time.
* The first episode of ''LightNovel/HaiyoreNyarkoSan''[='s=] second season has Nyarko drag Mahiro to a CosplayCafe where she, Cuuko, and Tamao sing "The Sun Says 'Burn, Chaos!'", the opening theme for the first season.
** Additionally, the first episode of each season has Nyarko quote-reference the previous adaptation's ending theme. The first season has her saying "That's right, I love you!", a line from "Like, Like, Love", the ending theme for the second ''Nyaruani'', while the second season has her saying "I promised to always [[GratuitousEnglish be with you]]"; "Always Be With You" was the ending theme for the first season.
* In ''Anime/SoraNoWoTo'' Rio sings a bit of the opening theme. But since she's completely drunk at the time, she makes an [[HollywoodToneDeaf absolutely awful]] job of it.
* In episode fourteen of ''MaicchinguMachikoSensei'', Machiko and her class sing the show's ending theme to pass the time on a bus trip.
* Episode 25 of {{Baby Steps}} has [[spoiler: Natsu and Maruo]] singing the opening and ending themes respectively at karaoke.
* In ''Anime/YoruNoYatterman'', Dorothy hums the opening theme tune for [[{{Anime/Yatterman}} the original series]] as she walks over to her husband's grave.
* Two in a row in the second season of the ''LightNovel/LogHorizon'' anime:
** In one episode, Isuzu sings a slow version of the ''first'' season's [[EndingTheme ED]]. Afterward, she [[LeaningOnTheFourthWall describes it as "a cover of something I heard long ago"]].
** She then goes on to cover the ''second'' season's [[EndingTheme ED]] in the very next episode.
* ''Manga/TokyoGhoul'' Episode 12 uses "Unravel" during the last scene.
* ''Manga/SoredemoSekaiWaUtsukushii'' has two instances:
** In a flashback with a young Livius in Episode 2, Sheila hums the ending theme.
** In Episode 10, Kara sings the ending theme at the concert, to her sisters' (and Neil's) bewilderment.
-----