Trojans—they're not just for hackers anymore. German police, for instance, love them; a scandal erupted in Parliament last year after federal investigators were found to be using custom spyware that could potentially record far more information than allowed by law. The story made headlines, but it lacked a certain sense of the bizarre.

Fortunately for connoisseurs of the weird, Der Spiegel revealed a stranger story in its magazine yesterday. According to the report, a top German security official installed a trojan on his own daughter's computer to monitor her Internet usage. What could possibly go wrong?

Nothing—well, at least until one of the daughter's friends found the installed spyware. The friend then went after the dad's personal computer as a payback and managed to get in, where he found a cache of security-related e-mails from work. The e-mails, in turn, provided the information necessary for hackers to infiltrate Germany's federal police.

That was bad, but it got worse. The hackers got into the servers for the "Patras" program, which logs location data on suspected criminals through cell phone and car GPS systems. Concerned about security breaches, the government eventually had to take the entire set of Patras servers offline.

One moral of the tale: parents, think hard before taking technical measures against your own kids. There's a better than average chance that they—or their friends—know more than you do.