I got sunburned (who would have thought - I had three jackets with me anticipating "normal" San Francisco weather :)
Some birds tried to mark my sketches.
Some smells from the farmer's market made me draw veggies instead of people and buildings.
Many sketchers looked at my sketchbook.
At some point people in line to get lunch blocked my view and while I refused to give up and continued glancing through them, they kept asking if I am standing in line or "just drawing here" :) Upon receiving my answer some would stand a bit aside and some would just get closer to me, yet some would take out their camera and literally get between me and my sketch :) It was fun - zoo like fun! (and I love sketching in zoos :)