The Schmilblick is an imaginary object created by the French humorist Pierre Dac during the 1950s. It is absolutely useless, and can therefore be used for anything, being rigorously entire. Pierre Dac himself credits the brothers Jules and Raphaël Fauderche with its invention.
The Schmilblick resurfaced in 1969, in a TV Show by Guy Lux and Jacques Antoine entitled The Schmilblic (sometimes spelled Schmilblik or Schmilblick). The aim of the game was to guess the name of an object given some of its characteristics (color, shape, use and so on). This TV game actually re-uses an idea from an old radio show created several years before and called Tirlipot.
Coluche used this word in one of his sketches, a parody of Guy Lux's show.
The word quickly became very popular in French language and was sometimes used as a synonym for thing or stuff, or something designating a strange or unknown object. Nowadays, this word is occasionally used to refer to some limited help provided by someone to solve a difficult problem. The idiom is actually faire avancer le schmilblick ("to make the schmilblick move/get ahead", literally) and was used a lot in the TV quiz show where it meant asking another pertinent question that might make it easier to guess the object.