Many years ago, my brother found a PC game called "Blood Bowl". Near as i can recall, it was basically a board game of American Football or something vaguely like that, but instead of fit young men, the players were Orcs and Goblins and such.
I think.
This was back in the DOS days. When computers actually were quite pricey.
So after weeks of my brother's pleading, I went to install it...
and...
... after install, I rebooted to try out the game.... my brother in tense anticipation....
... and the computer wouldn't boot up. Wouldn't do bugger all.
That CD-ROM had an exe that wiped my hard drive clean. Couldn't even boot up the computer because there was no OS on it!
Brother was confused. And I was in disbelief and really pissed off!
Years later I can laugh about it, but I was quite pissed at the time!
The game didn't cost even a dime. Just all my data and installs!