Stupid sharp pointy metal objects.
Was actually going to be early for work today, an unheard of occurence, and I ran over a piece of metal, puncturing my bicycle tire.
I guess one of the many bonuses of riding a bike to work is that when you blow a tire, you can just hitch a ride with a co-worker, rather than calling a tow-truck.
Now I need to buy a new tire. *grumble*