A Vietnamese person has 800 friends on Facebook, including 150 mutual friends with me. Under his posts, I see comments from my (and his) Polish friends who haven’t posted any comments on his profile before. These comments seem somewhat artificial, like "Happy Birthday." He also gets likes from Polish friends. How is this possible? Surely this Vietnamese person hasn’t hacked into 150 Polish accounts? Could it be some kind of script or chatbot posting on behalf of real people without their knowledge?