"Yatta!" is a 2001 parody song by a fictional Japanese band called はっぱ隊 (Happa-tai; literally "Leaf Squad" in Japanese, though they call themselves "Green Leaves" in English). The song title, "yatta", is the shortform of "yarimashita" a Japanese exclamation meaning "it's done!", "I did it!", "ready!" or "all right!" The song was first performed as a sketch on the Japanese sketch comedy show "笑う犬の冒険" (Warau Inu no Bōken; Adventures of a Laughing Dog), known as "Silly Go Lucky" in the United States, where Happa-tai, a sendup of a stereotypical boy band, is portrayed by some of Japan's most well-known comedians. It became extremely popular on the Internet through the distribution of its music video, as well as an animutation called Irrational Exuberance which used the song.
The song itself is a disco-influenced number, showing the influence of songs such as YMCA by The Village People. The video features its members singing and dancing exuberantly while wearing only underwear with a large green leaf on the front. The six band members' synchronized dancing and personalized poses for the camera parody the boy band craze.
The sketch satirizes many of the stereotypes of Japanese pop culture, including such tropes as a romantic interlude during the song's bridge that takes place on a city street filled with floating sakura blossoms.
On 2001-04-18, the "Yatta!" single was released under the Pony Canyon label in Japan. It surprisingly hit #6 in the charts, and went triple-platinum in Japan within a number of weeks. While the song was intended to be humorous, some viewers outside Japan assumed it to be earnest, perhaps due to the obvious work that went into the special effects in the video. The incomprehensibility of such an elaborate video enhanced its popularity among Western audiences who could not understand the Japanese lyrics.
The song and video have since been used as a web culture in-joke on many different websites. The actors who performed as Happa-tai were brought to perform "YATTA!" in the United States on Jimmy Kimmel Live. Host Jimmy Kimmel compared himself to Ed Sullivan introducing the Beatles in their first American performance.