https://en.wikipedia.org/wiki/Parsley_massacre

Also:

In 1937, Dominican dictator Rafael Trujillo – who wore makeup to lighten his skin and was obsessed with "whitening" the predominantly mixed-race island – ordered the massacre of Haitians in border areas, where many worked cultivating sugar. To determine who was Haitian, soldiers with machetes asked dark-skinned people to say the word "perejil", which is Spanish for parsley. For Creole-speaking Haitians, the "r" sound was difficult to pronounce, and a slip of the tongue became a death sentence. Estimates of the massacre range from 10,000 to 25,000 people killed over the course of a few weeks. And the bitter irony was that Trujillo's grandmother was Haitian.

https://www.theguardian.com/commentisfree/2013/oct/07/dominican-republic-haiti-long-history-conflict