some companies have a nice square concrete box in the smoking lot, and they add a new layer of concrete with the hdd inside

you could also, open the disc, and use some kind of powertool

or you could put that hd in another box, and run dd over and over again for some time,
make it random, no always 0 over 0

you can recover hdd info from a hd if it was deleted once, or twice. i have read about recoverng info after eleven passes., but im sure that if they are capable of using that tech, they could easily bribe another employe for the same info.
so just use dd a few times, and one or two hits with a hammer.
hammers always fix things

as a side note, do you know the guy from "will it blend?" ?