I suppose some of the other reviewers here may think I am a really sick person, but I thought this was hilarious! Prior to this viewing, I had never heard of Chris Morris, probably because I live on the other side of the Pond, but I will seek out more.
I won't recap the content because others have already done so on this forum. My reactions to this material are quite different from others' reactions, however, and I encourage the reader to take a chance and see what their own reactions will be.
As a clinical social worker who has worked extensively with the chronic mentally ill, I was not offended by the portrayal of an obviously deranged person. Persons experiencing psychotic episodes involving command hallucinations, whether aural or visual, are human, and the content and logic of their experience, while bizarre, is recognizably human. You may recall something you once believed and later found to be false or inaccurate in some way. To the extent that this belief influenced your decisions at that time, you were sharing the same mechanism that causes a psychotic person to believe a dog is speaking to them or the television is blinking in some mysterious way that may or may not be revealing something important. The difference is in degree and, possibly, in the lack or over-abundance of certain brain chemicals.
I give this a 9/10.