I had a stick caught between the cutout in the bottom of my shoe and the cleat the first time I fell. (I had been riding clipless for a few days so I "knew" what I was doing.)
I coasted past a line of stopped beach traffic and thought I had timed the light just right EXCEPT I forgot the turn arrow. So, I had to stop.
Tried to unclip to no avail and gravity got the better of me. The worst part of it (other than the fifty cars seeing it happen in super slo-mo) is that laying on the ground along side the road, my bike was still attached. I had to take my shoe off to get unstuck from my bike. (see earlier part about stick.)
I swore that day to never wear that t-shirt while on my bike again.