Kinda the opposite of "worst thing you broke", but once a friend of mine was having me build him a computer (probably around 2001, 2002) and he bought the processor from some crazy cheap Korean site. When it came it had a bent pin, but it was in the far corner, so I was like "I got this!" and grabbed a pair of pliers and tried to get it back into place. It wasn't pretty, but somehow it worked.
Same friend, a few years later called me up and was like "dude, what do you know about (first gen) MS ergo keyboards" and I was like not much why? He proceeded to tell me he took it apart, like COMPLETELY apart to clean it out, and couldn't get this ribbon to line back up so nothing worked. I just told him it was toast, and not to be so stupid next time. Like I'm going to fix that shit.
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Why does it burn?!