I bought a Genesis Activator, and used it one time.
I spent all of my rent money ($400.00) on a Sega Saturn the week it came out, without telling my live-in girlfriend.. and then had to return it a week later so that I wouldn't be evicted for not paying rent.
I walked into a Software Etc., slit open a PC Might and Magic 3 box, and shoved the 5 1/4" discs under my hat and walked out, risking being caught shoplifting, and then coming home to play it to find that it used a software manual keyword copy-protection scheme.
I decided to open up my Xbox360 Elite one night during some heavy drinking to "clean" it, and would up destroying it by clumsily dragging a screwdriver across the motherboard and scraping of lots of apparently very necessary circuity!
So many bad stories I could tell. What are yours?