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.

>>96
In other words: Hide a wireless node - preferably not on your property, use a propietary filesystem - preferably one you wrote yourself, encrypt this filesystem, and use a deadman switch.

Encrypt your harddrive with a keyfile and setup a program to delete the keyfile after 12 hours unless you intervene.