mountain biking.
I had spent the past 3 days in the Whistler Bike Park, hit a few goals for the week (no dabs on crack addict, clean full run of upper whistler DH to lower joyride to 4X, ect..) anyway, after that I decided to go dirt jumping the next day, nothing crazy, just some jumps in a friends back yard.
Near the end of the day I decided to go back to the big ramp to hit some bigger jumps. I get to the top of the ramp, clip my pedal while im rolling in. Flip over the bars fall 20 ft onto my head. leads to 3 fractured vertebrae, lacerated liver, lacerated kidney, concussion, torn muscles all through my back, and I brused half my face (Through my full face helmet) Also I nearly split my helmet in half.
After I woke up on the ground with all my friends telling me they thought i died I told them "Its okay, im dreaming. Just let me walk this off" I walked 20 feet and lay back down. 2 mins later the ambulance arrived.
TL;DR: Best week of riding in my life, clip pedal on steep ramp, break my everything. walk it off.