Of the many, this is my worst:
When you're working with a small part of some thing/object and you manage to drop it...
and upon falling, that little part manages to catapult itself magically to some hidden crevice or alcove somewhere nearby that sends you in a fit of frustration trying to find it.
The second part of this is when you keep looking for that part and cannot find it, and start to feel like there must have been a small rip in the space-time continuum that happened at "just the right moment" to essentially whisk that part away from your reality, never to be found again. Sometimes I have literally "lost" an item that dropped nearby, and even after moving furniture and anything else resting on the floor, it would not be found. In some cases, it would turn up later as the tiny item somehow bounced in just the right way that it landed into something where it would remain completely out of view.
Just to give you the idea of the probabilities I seem to attract for losing things:
In one case, it was a screw for a watch case. The tiny little screw rolled off the desk and bounced on the hard wood floor, rolling into "the netherworld." I didn't find it and eventually had to source a replacement. But months later, I found it. It had wedged itself into the tiny space of a book binding, among a small stack of books resting nearby. When I moved the stack of books it didn't come out. Somehow there was a tiny thread in the gap that the screw "hooked" onto. It wasn't until I picked up the book and held it vertically when that little screw fell out, onto my desk.
Another perplexing one was after turning over and moving so many things nearby, even emptying the waste basket carefully and finding nothing. What actually happened was the little part had bounced amazingly into the narrow gap between my foot and the shoe. My sock was thick enough and the part lying just the right way that I didn't feel it. Even when walking around the house. It wasn't until I took off the shoe that the little item shifted on the inner sole such that it would be in the right position so that the next day when I put the shoe on I felt "something" on the underside of my heel.
This kind of incredible seriously small chance of happening situation happens to me a lot. After enough times, I've had to take precautions to "contain" and help prevent this from happening. But, it's not perfect. One day I was cleaning out the cap of a fountain pen that I have. It uses a tiny spring in the clip to give it "spring tension". I'd taken off the clip to do a thorough cleaning on the stainless steel surface beneath it. Upon putting the clip back into place, I had to compress the spring while sliding it into the grooves of the cap. I did this in the bathroom, over the sink with the drain closed. But all of the sudden, *PAH-JING!" The spring escaped the compression and launched. I heard a little sound, but had trouble pinpointing it. I looked everywhere. NOTHING. The little spring could not be found. Not under the vanity. Not in the bathtub. Not on the shelves. Not in the little stack of items nearby. Not on the terrycloth bathmat. Gone. But, I found it... later. What happened was it attached itself to the bathmat in such a way that it wasn't plainly visible and didn't shake loose when I jiggled it. It wasn't until a month later, I got lucky. I was going to wash the bathmat and manipulated it just the right way that I felt something on it. I thought it was some debris stuck to it, only to discover it was that pesky little screw like a bug snug in a rug.
That's the kind of "can't find it" shit that happens to me more times than I care to mention.