If you're Bollywood star Shah Rukh Khan, you sign autographs on them. At least that's what happened when he found people holding copies of the scans of his body taken with one of the new full-body scanners at London's Heathrow, according to Yahoo India News. From the article:
'Then I saw these girls - they had these printouts. I looked at them. I thought they were some forms you had to fill. I said 'give them to me' - and you could see everything inside. So I autographed them for them.'
He's a way better sport than I would have been.