Worst error message I ever received is a tie between something to the effect of "Your MBR is missing" that appeared when booting and the smell of burning plastic that indicates you reversed the voltage on the new hard drive you installed because the modular cables your power supply came with were designed by an idiot and can be installed upside-down rather than using the standard "only fits in 1 way" connector and you didn't pay attention and installed them upside down. I do not buy power supplies with removable cables anymore.
The worst error message I never received but would have if the computer was working: "Hey, your stuffty case you bought for $20 is causing some kind of short that is keeping your computer from completing POST"
Also: no free edicts