At C3, a guy asked if I would take a picture with him to show his Karate class, seems he was the instructor. I said sure and without warning he had me twisted over in a very uncomfortable position. Not cool.
Or the time at a childrens museum displaying Star Wars props, when I tried to get on a elevator a mother went ballistic and pushed me out of the elevator because her kid might get scared. Kid did not looked scared, just the mom.