I had kind of an inverse experience to the one described by Open Eyes. It was with someone who pretended to have been a member of special forces in vietnam, when he was verifiably across the world in Canada taking photographs for newspapers that were archived locally with his name and date. He said he was on the third to last helicopter out of Saigon, and made up numerous other stories. He also would have flashbacks to terrible scenes of death in vietnam, experiences he had never had. He lied about big and small things but what was most profound was his invented life history. He claimed to be suffering and would pay a therapist lots of money to treat him for conflict related ptsd.

I have never met anyone like him and hope I never do again.