Sketches from my BC tour.
If nothing else, grab whatever scene comes into view - whether it be something you see out of your window - like this scene while sailing on a BC ferry from Port Hardy to Prince Rupert at the end of July 2011. I wasn't the only artist sketching on board, Laurie Collins from Australia was doing rapid watercolours from the stern. I can't show them here but they were very good.
You could try a shopping bag right before you.
Sometimes even an unsuspecting customer in the restaurant will do. (I DID show it to him upon completion but he pretended not to know who that gentleman was).
Lastly, copy a photograph from a magazine - remember to change it a lot so that you don't get accused of plagiarism.
I take a sketchbook just about everywhere I go - it's sometimes a relief from dragging a camera around.