It's wrong to post someone's conversation online without their permission.
Tom has a long and important business conversation with his friend during lunch.
Tom wants to let her friend know what he thought about their conversation.
Tom posts in a private message to his friend what he thought about the lunch conversation.
Tom posts publicly on Facebook to his friend what he thought about their conversation.
Tom's friend thanks Tom for respecting his privacy, and they exchange further details.
Tom's friend gets mad at Tom for revealing private info in public and Tom feels sorry.