One real life example: in Dutch you have the swearing word 'Mongool'. Used as swearing, it is to define someone as dumb, stupid or to mark a person that has the Down syndrome. 'Mongool' however is also used in Dutch to name someone with a nationality from Mongolia. The reason behind this is because in Europe there was a huge fear against the Mongolian hordes. Which you can't blaim them, considering the conquests of the khans. That fear even struck the area that would later form the Netherlands, while the Khans didn't manage to push further than Poland - which is quite a distance away from here. But despite that, a swearing word was made up against them. Because in older times, the word was used as to mark the child of a woman who gave birth to a 'mongool', was related to a female that was once raped by a Mongolian warrior, which were being downgraded back then as a lesser race (the link between them are the eyes). A funny fact because this swearing word has been around for over 700 years.