happened to me once when i was a learner...i was coming around a bend - a curve in the road, not a new road, and these 3 girls just stepped out...one of them smugly started sneering that i hadn't indicated - as though this 15 year old was teaching me to drive!
i shouted out the window, as they strolled across, that i didn't need to as it was single road with a bend in it, i was not turning into a new road, and when she grew up and was old enought to drive, she would learn that, and in future, she should check the road markings.
she just looked at me.
(there was another road that appeared to lead straight on from the road i was on, so i can see why she thought that though)