The 3DS's "StreetPass" function allows players to automatically trade Mii Avatars with whomever they pass on the street. But the streets are dangerous, and some 3DS owners are bound to be total dicks.
Offensive and Not Safe for Work language to follow.
"Dick" is actually a nickname that brings up a warning screen on the Japanese 3DS. So if your name is Richard, you better just stick to Rich. "COCK" is out, too, but "COCKSUCKER?" That's totally cool. The warning screen pops up whenever a nickname sets off the filtering software, informing players that the selected nickname could offend others and telling the 3DS owner to check his or her instruction booklet.
Different words trigger the warning screen. I entered a slew of profane Japanese and English words into the nickname section. For some reason, there is an assumption among some in the West that there are no bad words in Japanese. There are tons of bad words in Japanese. Many of these words are banned from television, while others are allowed on TV, but are simply considered crass.
Political correctness does exist in Japan as evident by the changing of "kangofu" (看護婦) to "kangoshi" (看護師). Both words mean "nurse", but kangofu contains kanji (婦) that pertains to women. Not all nurses in Japan are women, hence the change. Even words like "half" (ハーフ) that refer to half-Japanese individuals are now seen as containing elements of racism and are not said on news broadcasts. Instead, the Japanese equivalent of, for example, "French-Japanese" is used, among other terms.
I entered in worse words than this. Some of the words, like "kuso" (shit) or "oppai" (boobs), aren't that bad. Some of the slurs towards disabled people or minorities are. While entering these words, I even changed the window that lists who created the Mii to "Fuck You". This did not bring up the warning screen, and neither did "Fuck You" for a Mii name (as seen in the video).
Here are the words that brought up the warning screen: chinko (penis), chinchin (penis), chinpo (penis), ochinpo (penis), chinpoko (penis), ochinpo (penis), penisu (penis), PENIS, seieki (semen), aieki (semen), seishi (semen), zaamen (semen), manko (vagina), omanko (vagina), omeko (vagina), PUSSY, yariman (slut), ANAL, sekkusu (sex), SEX, reipu (rape), RAPE, goukan (rape), onanii (masturbation), FUCK, fera (fellatio), unchi (poop), unko (poop), BITCH, SHIT, shine (die), bukkorosu (to beat to death), rorikon (Lolita Complex), kichigai (lunatic), tsunbo (deaf person), buraku (Buraku are an outcast group in Japan), shinjin (slur for Chinese), chankoro (slur for Chinese), kuronbo (dark person), niguro (negro), NEGRO, katawa (cripple), chinba (cripple), pikko (cripple), WHORE, SLUT, ASS, DICK, COCK, DAMN, TWAT, CUNT and TITS.
Here are the words that did not bring up the warning screen: ochinchin (penis), kintama (testicles), tamatama (testicles), fuguri (testicles), chinge (dick hair), nikubou (penis), mara (penis), speruma (sperm), manjiru ("cream pie"), yarichin (guy that beds lots of girls), omanman (vagina), mange (vagina hair), kurito (clit), oppai (boobs), anaru (anal), fakku (fuck), Hshitai (I want to screw), ferachio (fellatio), cunni (cunnilingus), COCKSUCKER, paizuri (titty-fuck), UNKO (poop), geri (diarrhea), taiben (shit), kuso (shit), makiguzo (shit), bicchi (bitch), rori (Lolita), oshikko (urine), kojiki (begger), dojin (native), burakumin (Burakumin are an outcast group in Japan), hinin (lowest rank of the Japanese feudal cast), eta (lowest rank of Japanese feudal cast), domori (stutter), ketou (hairy foreigner), nigaa (nigger), rosuke (Russian person - "Ruski"), Amekou (American person), JAP and choppari (Korean slur for "Japanese people").
Note that the words in caps were entered in English, and the English version of the 3DS is bound to be different. Though, if these words seem familiar, that's because many of them were denied and allowed in Pocket Monsters: Black and White, leading to assumptions that the Mii Studio software is using the same filter. Some words that were not allowed in Black and White, like "hinin", are oddly enough allowed in the Mii Studio. And some words that were allowed, like "bukkorosu", now bring up the warning screen.