Worst crash I ever had on a bike was during a commute to work. It was winter and it was dark in the morning, and the bridge over the river had gotten icy. I hit my brake and slid, went straight into the retaining wall on the embankment, headfirst over my handlebars. I'm fucking lucky I was wearing my helmet.

Ended up putting a decorative bandage over the scuff on the helmet shell where I would have split my head open. It looked gnarly. I got a new helmet first thing as soon as I got my next paycheck. Kept it on a shelf for a while.