Back in my undergrad days, there was one fine Sunday morning when I needed to swap a couple of hard drives around, i.e. the master would become the slave and vice-versa. This was specified with jumpers, but unfortunately I didn't have enough to actually do the job (you only needed one for "master mode" vs two for "slave mode", and the stingy manufacturer hadn't given me a spare). Hmm. However, one of my friends from the CompSci course had come over to visit, and he came up with a solution to this problem. I had an old (broken) pair of headphones, so we cut a piece of cable off that and trimmed away the plastic to get some copper wire. This then got wrapped around the relevant pair of pins, and we stuck some blu-tack on top to hold it in place. Job done! After all, that's all that a jumper really is, i.e. a conductive wire inside some insulation. Later on, one of my flatmates (an engineering student) woke up, and was horrified at this bodge-job. Meh, that's what you get for having a lie-in :) Anyway, this worked smoothly until I outgrew the drive.
Today I had a vaguely similar problem at work, where I couldn't plug a keyboard into the back of a server (PS2 socket). On closer inspection, it turned out that the black plastic pin from a previous keyboard had broken off inside the socket, so it was stopping the new plug from actually going in far enough. I tried to fish it out with blu-tack, but sadly this trusty source failed me; the hole was too small to push my finger in, and a paper clip couldn't push enough in. I did a usenet search (on the grounds that I'm rarely the first person to encounter any specific problem), and someone had suggested putting a small amount of superglue on the end of a toothpick. In theory, this could work well - the glue will stick very strongly to the broken piece of plastic, and pull it out easily. In practice, I suspected that my hand would twitch at the wrong time, and I'd wind up with a toothpick welded into the socket, and protruding a couple of inches out of the back of the machine; not a great improvement. I didn't have any tweezers that were small enough to fish it out, and trying to pry it out with a paper clip didn't work; I was able to chip a couple of bits off it with a scalpel, but that was pretty haphazard.
Plan B: It turns out that the black plastic pin isn't actually essential, i.e. it's not metal, so it's not carrying any current. Its only purpose is to help you get the cable positioned properly, since it will only go into the socket if it's the right way around. So, all I needed to do was trim that pin down to a shorter size, and I'd be able to get the plug into the socket. (Fortunately, I have plenty of sacrificial keyboards lying around.) This is another case where health and safety guidelines don't quite apply; I had to put my hand all around the plug, so even though I was cutting away from my body, I was still cutting towards my fingers. Anyway, I managed to trim it down without any bloodshed, which was a relief. And that did the trick - I was able to actually use the keyboard after that.
So, singalong at home! "Oh, I've been trimming at the cables..." (to the tune of "I've been working on the railroad...")
Everything I need to know I learned from MacGyver :)