Actually, more often referred to as a dutch angle, it is a specialized camera angle that does not employ the normal horizontal and vertical axis. Often the primary axis becomes a diagonal with the intent of eliciting a disconcerted effect in the audience. Psychologically the effect can be used to bring the audience into the uneasiness or anxiety of the character and the situation depicted on the screen.... with thanks to Film Glossary...
Glossop I ask this question here because I asked this question in a Theory of Film lecture and my friends thought I was taking the **** for that very reason! I find it funny that it came up here again. ROFL.