How was it possible for me to snap the bone in my big toe last night without noticing at the time?

I woke up this morning, & the big toe on my right foot was really sore… no bruising, but then I rarely ever bruise. The Dr in the office next to mine just took a peek as a favour & it appears that I’ve snapped the bone in the end bit of my toe, right across, roughly at the same place as the start of the nail. I wasn’t aware of doing this last night, & I wasn’t drunk…. any ideas anyone?