Oh, I see. You mean you want to walk around in the street shooting people and pretending you are not there. The ideal solution would be to have an invisibility cloak, but that's future. More practical solution for today is to disguise as a walking advertisement, make a hole in one or both boards, and stick the lens through the hole.
I'm being sarcastic only because I don't get the point of photographing people in a way they don't notice you. Golden days of voyeuristic photography are gone, and remember that photography is interaction, not action. You are shooting people, not game.