In the UK we call it Sod’s law, also know as Murphy’s law. If anything can go wrong, it will.
I had one memorable one years ago, My Basenjis decided to make her own way home while out on a walk, and instead of going under a bridge and avoiding the traffic she choose to go over it and through the traffic!
Needless to say she had been run over for the second time in her life and was in need of veterinary help, so I jumped in the car and turned the key, the engine momentarily tuned over and came to an abrupt stop, the cam belt had broken. Why now of all times!
So at great expense a veterinary ambulance was called, the next day she was right as rain with just a few stitches to show for the ordeal.