So uhh, I've broken a LOT of hardware...
1998: (Not so much broken, just scared the crap out of me.) Just gotten my very first brand new Windows OS computer, Pentium MMX @ 233Mhz (not the P2) with 32MB of RAM. I had never really seen or played with a "modern" BIOS at this point, and started tinkering, figuring out what I could switch to make the system either boot faster or operate faster. I managed to inadvertently configure BIOS for no IDE devices installed, so the system simply stopped trying to POST. It took me a week of agonizing over admitting to my grandpa that I broke the brand new computer he got me, or try to find somebody to give me guidance; I ended up talking to my friend's dad who was far more into computers than I, and recommended that I just reset CMOS... I felt really dumb, and then really emboldened to see what I could do with it. I never told my Grandpa. Lesson learned: Don't play with stuff unless you know how to undo it.
2000: First Windows computer (from above), upgraded to 256MB. Original board had 2 PCI slots on it, 3 ISA, and 2 ISA-Extended slots. I had done some work inside the case flipping DIPs to try to overclock my CPU (to very limited success), and had forgotten to re-install my ISA 56k modem. I happened to call a friend who wanted to play C&C Red Alert with me, so I got off the phone and proceeded to go to my computer to get ready. I had just learned that PCI was supposed to be hot-pluggable, and assumed ISA was the same. Attempted to plug my modem into my PC while it was on, POP, no more computer. It was a sad month until I saved enough to both find and purchase a replacement Socket 7 mobo (they were already phased out and hard to find). Lesson learned: Make sure you know exactly what the hell you're doing before doing.
2003: Blew up an AMD Duron that I overclocked almost instantly. System managed to start booting Win XP, then loud POP with a small waft of smoke out of the case, and that CPU/board was done. Lesson learned: Don't buy cheap CPUs and try to OC them.
2011: Rebuilding my home-built pfSense router, I was mounting the CPU (Athlon x2 4200+) back into the socket (Socket A, it had the flathead screwdriver spot to help mount the clip), and my screwdriver slipped, hitting the back of the GPU, severing a number of traces on the board near the slot. It rendered that poor 8600GS lobotomized to PCIe x8 from PCI x16 and if it was in an actual x16 slot, it wouldn't even POST. Funnily enough, that same router config is still running to this day, just GPU now in x8 slot for life. (And yes, it does push Gigabit speeds without breaking a sweat.) Lesson learned: Avoid Socket A fan mounts.
2013: First (and so far only) 8-core computer rocking an FX-8120, all core OC'd @ 4Ghz 24/7 with Corsair H80 in push/pull configuration. Came home WAY late one night after being out with the roommate to find that unmistakable stench of blown electronics, and my computer dead. I had bought a cheaper gaming board with OC capability, but no power phase heatsinks, and then took away any airflow down onto the chips by going watercooling. Board and CPU died instantly, everything else was salvageable. Lesson learned: Don't leave heavily OC'd hardware unattended, and don't cheap out on components if you plan on OC'ing.
2018: Dumped ~1 liter of Cherry Coke into my Razer BlackWidow Chroma (v1 with the 5 macro keys), it survived after a vigorous rubbing alcohol and warm water bath, though, the switches are now starting to stickkkkkkkkkkkkkkkkkkkkkkkkkkkkk. Still rocking the half-broken thing. Lesson learned: Do NOT keep sugary drinks on my desk. (I still do, just much further away from my keyboard.)