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.

Don't use a hard drive. Boot off a LiveCD and keep everything in RAM. If the cops arrive, all your CP will disappear the instant they unplug the computer to take it away for evidence. For maximum mindfuck load the whole OS into RAM and remove the CD, so when they get to the station they find a computer totally lacking any storage medium. Works best if the computer is on when they arrive so that they can see it running.