"Yatta!" is a 2001 parody song by a fictional Japanese boy band called Green Leaves (はっぱ隊, Happa-tai?). The one word in the song title, yatta, is the past tense of the Japanese verb yaru ("to do"), an 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 Adventures of a Laughing Dog (笑う犬の冒険, Warau Inu no Bōken?), known as Silly Go Lucky in the United States, where Happa-tai is portrayed by some of Japan's most well-known comedians.
The video features its members singing and dancing exuberantly while wearing only underwear with a large green leaf on the front. The seven 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 April 4, 2001, "Yatta!", written by Hideki Fujisawa as Dance Man (dansu man;ダンス☆マン), who wrote songs for Morning Musume, a TV animation Sgt. Frog and so on, 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 lyric(s).
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 US on Jimmy Kimmel Live!. Host Jimmy Kimmel compared himself to Ed Sullivan introducing the Beatles in their first American performance. The band's appearance was referenced again during Kimmel's interview with Masi Oka.