The strangest occurrence was shortly after I had finished restoring my granddad granddad's Rudge, I came back from a ride, went to put it on the kickstand, the crank was in the way so went to move the pedal with my foot when it dropped to the ground - the spindle had snapped off right on the inside bearing cone. Not a fresh break, I assume it had taken an impact at some point but a few minutes previously I had been climbing out of the saddle which could have been very painful.
I also stripped a swaged steel chainset onmy fixed wheel Carlton.
Just this morning on a 3-speed bike, I ran over a stick which somehow shot up and got between the hub and the sprocket and popped the sprocket and circlip off the hub. Easy enough to fix but surprisingly tricky without my favourite little screwdriver I use for doing this at home.