Something came to mind, something I remember:

When I was manic I would stand up on a stage (which was usually with my hands elevated on a table or tiptoes- which I was imagining was some kind of a stage where I could proclaim my greatness) and begin declaring loudly that I am destined to be a great philosopher or I am clairvoyant, it happened every time I was extremely manic with psychotic features, it would happen at my house with my family and even at the hospital, I hadn't slept one night and when everyone was gathered around the table I stood up on the table and was, again, loudly declaring my greatness and how I was clairvoyant and knew all, and was a "like a mirror" I do remember some of the reactions I got, I don't know if I was affected by them though, I have no idea, but that is what I believe was grandiosity.

I truly believed what I was saying too