How to explode a hard drive

I know this isn't strictly tech, but I felt it's the best place for it.

People talk (on 4chan and such places) of raids by the police on their house to recover hard drives due to suspicions of CP or of pirated content.
I was wondering if anyone knew of a case where someone actually managed to destroy their Hard Drive, either remotley or before anyone could get to it, or any stories of the sort.
Could it hypothetically be fitted with some sort of... remote water filling thing?
Post anything relevant please.

Saw an episode of Law and Order where a guy had hidden a degausing loop by the door.  When the police walked out the door it wiped the hard drive.  Don't know if that would actually work or not, or how powerful the loop would have to be, but I've seen TV repair men build their own out of old extension cords.