If you have ever taken a naughty picture, you could be at risk of revenge porn. Particularly people posting it on Facebook. I read about this on XXXBios at
Basically Facebook have found their own way around it - you send them your nudes and then if they see those pictures posted online, they automatically take them down. Particularly if your ex unfriends you - it allows you to get the pictures offline and potentially know they did it (I don't know if Facebook tell you). Otherwise if they posted them and you can't see it - your nudes could be online.
Revenge porn is illegal and I hope all the people posting pics of their exs go to jail!