I had just recently got my first computer that I'd waited for a long time with my first paycheques from my first job - an A500. I couldn't afford a monitor yet, so I had some old heavy 20" TV as my monitor. The TV was sitting on the top tier of some cheap Ikea MDF desk. I had picked up TV sports football I think, and just left the demo loop running so I could sit back on my bed and admire it all.
Well the TV was too big for the top tier, and I had somehow left it balancing precariously. The TV slipped off the top tier on to the amiga, and the desk imploded and the whole thing ended up on the floor. I was totally freaked out. Luckily it all seemed to keep working, but the desk needed some work to make it stay together again.