Gaki no tsukai

Downtown's Gaki no Tsukai ya Arahende!! (This Ain't No Job For Kids) is a Japanese variety show hosted by the two very popular japanese owarai duos, DownTown (consisting of Hitoshi Matsumoto and Masatoshi Hamada), Cocorico (consisting of Naoki Tanaka and Shouzo Endo), and comedian Hosei Yamasaki.

Batsu Game

Probably the best known Gaki episodes are those dealing with batsu games, or punishment games, which one or more of the cast must undergo after losing a major game or physical challenge. The best-known Batsu Games include one in which the entire cast (except Hamada) are sent to 'school' for a day, during which various absurd things happen and the cast are punished for laughing; a game set at a "haunted" ryokan, at which Matsumoto must spend the night; and an infamous 24-hour Batsu Game in which the cast (minus Matsumoto) are locked in a sports arena and subject to being chased by "demons" at random moments. They've also made early batsu games such as No Laughing in Yugawara, and No Laughing in Hot Spring.

English Lesson

This segment, part of the longer school Batsu Game, is perhaps the best known outside of Japan. The cast sits in a classroom watching a T.V. What they watch is a man, comedian-turned-artist Jimmy Onishi, reading an English article about Marco Polo, counting in English and saying all the days of the week in English. He seems utterly bewildered by the English language and makes embarrassing mistakes. The objective of the game is for the cast to refrain from laughing; each time they do, a masked person comes in and hits their behind with a shinai. The video of this can be viewed at youtube.com

Silent Library

Silent Library is also a part of Batsu Game segment in which 6 members flip random cards, and do unpleasant acts upon choosing the bad card. They must remain silent during the entire session.

Chinko Machine

In this Batsu Game, the participants have to recite a really long, tongue twister-like promo for the show without messing up. If a participant does mess up, they take a run on the “chinko machine”, literally the “penis machine” or "dick machine", which releases a switch that hits the participant in the crotch. This Batsu Game was featured on the August 1, 2006 Oddball segment of Countdown with Keith Olbermann as "Reason Number 261 (of 527) why Japanese television is better than ours."

7 henge

Shichi-henge (The Seven Apparitions) is a segment of the show where the whole cast sits at a table while a comedian attempts to make them laugh. Each person who laughs must put 1000 yen into a box, which is later given to a charity of the comedian's choice. A variation on this (Horror Shichi-henge) involves seven members of the cast and crew ambushing a high-strung castmate with the intent of causing him to lose his composure - and thus be forced to surrender money.

Guys from Gaki can even sing! Yamazaki wrote nearly 30 songs for this show.
On youtube you can find some their songs like "Not a errand boy".

sources: wikipedia.org and google.pl