you just need a photo of them and an embarassing secret / spurious fact to reveal
the result is what looks like a video blog asking your friend to 'come clean' about their secret... the person in the video holds up your friend's photo and writes down what it is you reveal about them and shows it to the camera. they make it look like 50,000 people have already seen the video and there are comments left about 'people knowing that person.. what a sick bastard etc.'
did it to a friend yesterday. caused blind panic.