Twice. Once by someone turning right on a red, head turned to see if the traffic cleared and who didn't bother looking straight ahead before moving and I was in the crosswalk; and once by someone who drove through a crosswalk, stopped to park, I believe realized they weren't in a parking spot, and backed into the crosswalk after I had started crossing. Both times I was in the centre of their car and thankfully a soild whump of the hand made them stop.