is when the odds of something bad happening are extremely small yet it happens anyway.

e.g. been meaning to show my mum a bunch of photos I took over summer and she's been asking to see them. Just thought right now oh I'll show her those photos at last. I open my laptop and it decides to install this fucking huge Windows update. "Don't turn off your PC. This will take a while." It's been going for 20 minutes and it's still only on 16%. It's had all week to do this. It decides to do it at the moment I chose to show my mum the photos. FUCK RIGHT OFF.