In a professional setting: disappointment is the strongest word I’ve ever said to someone

Outside that? I don’t know if there is a good cutoff between slur/not slur… The one I vividly remember was old Chinese social media users (before the blockage) calling some people “Wumao” (translates to 50 cents). This is implying that the person is being a troll, and they did it because they were so pathetic that they accepted a 50-cent commission from the government to say good/bad things on the internet. Probably still the worst insult I could imagine till this day