I'd like to shake them up a bit, show them something creatively "scary" to help them realize the issues that come with giving away data.

Some additional information:

- This is a Western European country (no real issues with privacy since WWII);

- They don't mistrust the government ("Big Brother"-style arguments have little effect);

- They have little financial/working experience (arguments such as "your insurance will cost more" or "your future employer might not hire you" are inefficient);

- They haven't had enough partners to be really concerned about things such as "your future partners will know everyone you went out with".

Some ideas (untested, since not practical):

- Compile a virtual profile with everything publicly available about them, especially photos, which seem to provoke a stronger reaction than factual data such as addresses, names of relatives, etc. Problem: requires too much manual effort.

- Find out their e-mail addresses (if publicly available) and trigger "Forgot password"-style messages, to simulate them being targeted by hackers. Problem: borderline ethical.

- Apply some form of spear-phishing using information publicly available, such as "Hi Jane, this is Mary <family/friend's name found via public information>, I got this link from John <another family/friend's name>, it's quite funny!". Problem: requires too much manual effort.

Otherwise, I'm afraid I'll have to resort to listing some actual cases of teens abused due to exposing their data, which is not as efficient ("that would never happen to ME!").