Cx means a big smile face, if you turn to the side, you could see it.
Chat with our AI personalities
"cx" does not have a literal meaning it more represents a typed facial expression. It represents a happy/surprised face.
If they say 'Inbox me!' or something like that they mean they want you to add them as a friend on facebook.
What you said
fbf
It means you can chat to people on Facebook who are your friends and are online when you are.