To properly understand a film like this, viewers from foreign countries should consider two things. First, that the adjective 'green' of the title has sexual connotations (like 'blue' in English). Secondly, that during Franco's dictatorship everything related to sex (especially in movies, magazines, or books) was strongly censored. That is why the protagonists of the film, as a result of the repression they suffer in their own country, must go to the south of France to see "Last Tango in Paris" and other productions banned in Spain because of its high erotic content.