Awakening of the Beast

Awakening of the Beast Portuguese O Despertar da Besta, also released as O Ritual dos Sdicos is a 1970 Brazilian horrorexploitation film directed by Jos Mojica Marins. Marins is also known by his alter ego Coffin Joe Z do Caixo. Marins appears as himself and as the Coffin Joe character in the fictional film which is in the form of a pseudodocumentary.

Dr. Sergio gathers the four volunteers, and after receiving an injection, the volunteers four drug users seen in the previous segments are instructed to stare at a movie poster of Marins The Strange World of Coffin Joe. The film changes to color and each patients experience is vividly portrayed in a series of surreal scenes.

Source: Wikipedia