try to get a person on the street to try your food
Try to get a stranger to pee in a cup for you. Whey ask why DO NOT SAY IT IS FOR A DRUG TEST. Say your a collector.
at a restaurant, ideally one with outdoor seating, run up and take a bite of someones food and book it
Have your buddy pose as a "Photog" and have him take pictures of randoms and you just ruin the whole picture in the background.