Yeah. Not being familiar with a particular culture's stereotypes might mean not genuinely knowing why references to African-Americans and fried chicken/watermelon might be problematic (I didn't know about that one until a few years ago, because I am not American). This one is something else. And even if you aren't familiar with a particular stereotype, if you do use it, the appropriate reaction isn't "I didn't know, I didn't invent them, so leave me alone!"