Bored at work one morning, I was looking for things to tryout in the config.sys file of a very old Dell 386 (16MHz I think - cutting edge then!). Came across this file keyboard.sys, hmm, I wonder what that could do - entered DEVICE=KEYBOARD.SYS in the config.sys, re-booted and it trashed the hard drive.

Spent the rest of the day rebuilding it.