Nyoro~n (Japanese: にょろーん) is a catchphrase of Churuya-san, the super-deformed version of Tsuruya from The Melancholy of Haruhi Suzumiya, in the 4-pane comic series "Nyoro~n Churuya-san" (にょろーん ちゅるやさん) by Japanese illustrator eretto.
On June 15, 2006, the first illustration of the super deformed version of Tusuya named Churuya-san was posted to eretto's web page Utsra Uraraka. Two days later, he posted the first 4-pane comic for people who rejoiced at his Churuya-san illust. Her name, Churuya-san, sounds like childish mispronunciation of Tsuruya for Japanese sensibilities.
English Version (Here is the original version.)
Her adorable defeat expression "Nyoro~n" with the "<:3" face began quickly spreading over the web via blog posts and Haruhi-related threads in the Japanese textboard community 2channel. A huge amount of Shift-JIS arts for Churuya-san had been made by 2channel users and those are archived into the wiki page for Churuya-san.
Parody illustrations for Churuya-san became to be uploaded to the web after pixiv launched in 2007. On the other hand, Churuya-san was soon importetd to the English-speaking web via Haruhi fan communities. Fan arts and parodies for Churuya-san have been uploaded to deviantART since July 2006.
The popularity of Churuya-san had been increasing so much by new episodes of "battles her way through life to get her favorite treat, smoked cheese." that he continually posted to the web page. These episodes were compiled into a doujin comic book series titled "Nyoro~n☆Churuya-san" (にょろーん☆ちゅるやさん) which released three volumes from August 2006 to October 2007, and made a huge success in the doujin market.
In the summer of 2008, Churuya-san finally got to be included into the official Haruhi franchises by Kadokawa, the publisher of Haruhi series. The manga started to be serialized in Kadokawa's monthly comic magazines from September 2008, and its comic book and a Nendoroid figurine for Churuya-san were released in September 2009. In addition, it was also animated and webcasted on Kadokawa's official YouTube channel from March to May in 2009 along with the official spin-off title The Melancholy of Haruhi-chan.
Comic Cover, Nendoroid & Churuya-san the animation: ep1
Due to the cute nature and gag style comedy, this comic is very commonly parodied using characters from other anime series. The gag usually goes like this-
Pseudo Churuya: "Hey [insert name]!"
Other Character: Huh?
Pseudo Churuya: [Question, usually cute, obvious or characteristic of the own series]Eas
Other Character: Denial
Pseudo Churuya: Nyoro~n.
This exchange can vary, but this is usually the basic structure of the gag.
Left: Kyu Kyu Kyu Nya~ Dance | Right: "Pop Star" from Kirby 64