I just did a metric century today (Tour de Poway) and about halfway through I got a headache. I thought it was my helmet at first because it ached where the straps touched my head. I loosened the straps and it didn't help. I had ridden many miles with this helmet with no problems so I couldn't understand why I was getting this headache. I did feel weak in general, but that might just have been because of the ride.
So I thought I might be dehydrated. I started drinking everything I had on me, but it didn't help. Then I thought perhaps I'm bonking, so I stopped and bought a coke and some trail mix at a CVS. Within a few gulps of the coke, I was feeling better. By the time I finished the 20oz coke, the headache was gone.
Was that a bonk?