> I wonder if https://en.wikipedia.org/wiki/Buffalo_buffalo_Buffalo_buffal.... has a Japanese equivalent, or perhaps just 100% hirigana will easily confuse this, thus making context-dependency a necessity.

I'm not aware of Japanese equivalents (probably due to my lack of Japanese knowledge), but the Gyeongsang dialect of Korean language allows a sentence that only contains a single syllable 가 (ga) and thus can only be distinguished by intonation. "가가 가가가" is a commonly cited example and pronounced (here denoted using X-SAMPA) and analyzed as follows:

    가  ka:     The kid (short for "그 아", itself short for "그 아이")
    가  ga      [topic marker]

    가  ka      The family name "Ga"
    가  <R>ga   A suffix for family (collective, unlike "씨" for individuals; e.g. "김가" for Kims)
    가  <F>ga   Coupla, weak question

The dialect in Toyama, Japan has the famous "かか、かーかーかかーか" which decomposes/translates to:

  かか、 mother (お母さん in standard Japanese)
  かー this (これ)
  かー this way (こう)
  かかー write (書く)
  か ? (か)

In proper English, that would be "Mom, is it spelled this way?"

For repetitive sounds, there used to be a fun English example on Wikipedia:

> Ted and Ed edited it.

I'm vaguely aware of two meant for Japanese, though since I know no Japanese, there are almost certainly errors in my report here:

> "Let's cover Eastern Europe", to-o-o-o-o-o-o-o-o-o.

> "Two chickens in the front yard and two in the back yard", niwaniwaniwaniwaniwaniwatori.

I don't know if this is a widely used description, but there is a subreddit for this kind of thing, called "word avalanches". Some are purer than others.

https://www.reddit.com/r/WordAvalanches/

It is indeed SEO spam, although atypically well written and informative. At the bottom of the post, they encourage you to pay $2/day (!!) for their learning service hosted at a real .com domain.

The spam pattern becomes clearer if you look at the posting history for articles from this site: https://news.ycombinator.com/from?site=learnjapanese.best It's a pretty consistent pattern of once every couple of days.

If you look at the post history for the spammer's main account, they try to disguise their spamming by posting a few miscellaneous Wikipedia articles and the like between posting their site: https://news.ycombinator.com/submitted?id=sova

You can also see them experimenting with spamming their other sites as well; the poster is always the same individual.

https://news.ycombinator.com/from?site=japanesecomplete.com

https://news.ycombinator.com/from?site=learnjapanesebest.wor...

There are but I could not find many details about them in English. Some of the well knowns are:

すもももももももものうち or ははははははははのははははははとわらった

Please see MeCab (https://en.wikipedia.org/wiki/MeCab) segmentation output below:

http://www.edrdg.org/~jwb/cgi-bin/mecabdisp?sent=%E3%81%99%E...

http://www.edrdg.org/~jwb/cgi-bin/mecabdisp?sent=%E3%81%AF%E...

Mecab fails miserably on the second. It doesn't find the hidden "母は", but it's hard to blame it.

Tge german wikipedia page for buffalo has some examples in other languages:

https://de.wikipedia.org/wiki/Buffalo_buffalo_Buffalo_buffal...

In japanese: 子子子子子子子子子子子子

In swedish: Bar barbar-bar-barbar bar bar barbar-bar-barbar

In german: Weichen Weichen weichen Weichen, weichen Weichen weichen Weichen

子子子子子子子子子子子子 is a different category: in Japanese, Chinese characters usually have multiple possible readings. In the case of 子, it can be read as ko, ne, shi, or ji. 子子子子子子子子子子子子 is a word play that switches between them. It reads neko(no)kokoneko shishi(no)kokojishi. Note the no are omitted, which would be unusual here (although there are cases of all Chinese character sentences, but they are plain Chinese read as Japanese, with Japanese grammar made up on the spot). The actual correct way to write that sentence is 猫の子仔猫、獅子の子仔獅子.

The closest thing is にわにはにわにわとりがいる (庭には二羽にわとりがいる。)

> if I came across this domain name in a search engine result page I would think it was yet more SEO spam

Their main landing page doesn't inspire much confidence either: https://japanesecomplete.com/purchase The combination of layout and font gives that sketchy feel. I'm sure the content itself is great, but I think it would benefit from a bit more carefully constructed site along with some sort of trial (á la Wanikani) since almost every resource claims to be the panacea you've been looking for.