When I spend minutes/hours/days looking for something that needs to be turned in before the deadline and a few days after the deadline passes I find it without even trying. Feeling's even more frustrating when you keep looking in the same place you last saw it only to find out later when it's too late that it dropped and hid itself or someone put it somewhere else. Even more frustrating when you ask that someone when you're trying to find it if they put it somewhere only to have them bitch at you that you can't keep up with anything and then they magically remember when it's too late that they are the ones responsible for it being misplaced and don't apologize.
, If I wasn't a Christian
Also accidentally saving over your last game file that had a scarce item you spent hours to find, saving over an important class project, and saving over an amv project. All scenarios happened to me once so I should consider myself blessed.