Civi wise...... changing the wing attachment bolts on a Citation Jet, I got it all stress jacked so the bolts were loose and free to move, pulled the bolt out, pushed the new one in and 3/4's in, a fly must have alighted on the wing as the bolt went stiff, it took me two days of struggling and adjusting the wing and fuselage jacks to get the bolt back out and another new one in.... I just kept saying to myself one day I will laugh at this as people avoided coming near for fear of getting roped in.
RAF wise doing a booster pump housing change on a VC10 out on the line, crawling around in inches of fuel, deep into the wing and plugged into a compressor to breath.
Dropping a socket off the top of a tens engines and shouting down to ask if anyone can see it, to be asked what size is it?..... As if there were various sizes scattered far and wide lol.