When someone judges you without gathing sufficient information to do so. You are offended not because you care what they think but because they have not exercised due diligence when forming an opinion about you.
A: "...and now they think I'm racist"
B: "But you ARE racist"
A: "But they don't know that. Its premature judgulation!"
B: "Sure they do. I told them you are a racist"
A: "Oh. Thats ok then"