How are you? How old is your friend? How long has he been acting this way? Your friend may have schizophrenia. This is a psychiatric diagnosis that describes a mental illness characterized by impairments in the perception or expression of reality, most commonly manifesting as auditory hallucinations, paranoid or bizarre delusions or disorganized speech and thinking. Diagnosis is based on the patient's self-reported experiences and observed behavior. No laboratory test for schizophrenia currently exists. Social problems, such as long-term unemployment, poverty and homelessness, are common. If your friend permits, it would be best to visit a psychiatrist for proper evaluation and management.
I hope this helps. Take care and keep us posted.