probably the only way is to chose an image that is not already on the internet. So a printscreen maybe. Thats what i used when i made the thread "wich movie is it?". For some printscreen google would find a close enough existing image, for other printscreen he wouldn't
hint: get a picture from an obscure movie (and with said person being a minor character) and then stick it through imgur after first doing enough f***ing around with the picture so its recognisable for a human but not for google.