A documentary style film that is designed and presented so as to shock and possibly anger the audience towards the subject of the documentary. The views presented are usually one sided and in some cases are based on conspiracy theories.
"Farenheit 911", "Loose Change", "Walmart: The high cost of low prices" and "Who killed the electric car?" are all examples of a shockumentary.
A documentary-style film meant to shock and disgust its audience. These films tend to contain snuff footage (real and/or fake).
Faces of Death, Autopsy, and Cannibal Holocaust(to an extent) are all good examples of what a shockumentary film is.