My own example is rather sad. Two miles from the village I lived in is a large college internationally famous so it always has many foreign students. One day (I was 16) I was in town and happened across an African man (who was Kenyan). I said hello and struck up a friendly conversation with him, asking him where he was from and what his home country was like, and what he thought of England and our village. And he told me he was amazed that I had approached him because he had been in town 2 hours and no-one had spoken to him and he had been completely ignored, even when trying to buy things in shops. That was the day I realised I was living in a racist community, before I had had no idea