[Sacho]

I believe the underlying idea behind "dick pics" is that people are guided to think of something that is embarrassing to them. When you tell people they should stop using Facebook if they want to protect their privacy, they think of all the things they've freely shared and associate Facebook with positive memories - my friends liked my post, they laughed at it and shared it. When you make them think of "dick pics", they think of something that is taboo to share in most social circles, and associate it with embarrassment/negative memories.

The issue is that many of the things people share on Facebook/Twitter/etc are actually "taboo", and people's evaluation of them is just wrong. As an example, the story of Justine Sacco, a person who would arguably be even more aware than the average of the impact of public statements, still did not manage to correctly evaluate that the things she was sharing on Twitter would lead to a serious backlash and witch hunt against her.

The worst part is, you won't necessarily get instant feedback, like Justine did. You may post something "among your friends"(in reality, publicly on Twitter), all your friends may agree with you, and then several years down the line you will be judged by a completely different social group, looking through your records. We don't tend to accommodate evolution in people's beliefs as much as we do for ourselves - try the defense "I'm not that kind of person anymore" to strangers and see how often it works out(no need to try on your own, just check out how easy convicted felons have it when trying to reintegrate into society).