off the wall

Definitions

General English

  • adjective
    (written as off-the-wall)
    very unusual and strange

Slang

  • adjective eccentric, unusual, way-out. A phrase (possibly inspired by the unpredictable trajectory of a ball or an ice-hockey puck rebounding from a wall) which has been adopted outside the USA, usually in connection with zany and/or creatively original ideas or behaviour.
http://www.dictionarycentral.com/definition/off-the-wall.html