Brain Wall (脳カベ, Nōkabe) is a component of the Japanese variety show The Tunnels' Thanks to Everyone.
Video clips from the show proliferated on video-sharing websites and the concept was eventually adopted by several other countries.
It became popularly known to non-Japanese speakers and YouTube fans as simply Human Tetris or Hole in the Wall, named for its involvement of the physical body and a supposed close resemblance to the rules of the video game Tetris.
The first component of the game involves a solo contestant, while later components involve groups of two people or more.
The production rights to the show outside Japan is owned by Fremantle and the program has been produced in over 45 countries.