It means you have not been talking to that person as much as before and that you have become like a "stranger" to them. Yes, it's a sarcastic way to say "what's up/how's things going?" to someone who has not talked to you in a while.
It means Your friend wants you to talk to him/her more often than you do .
If you really like that friend , just try to contact him/her more often than you do now , otherwise , just ignore it .
Good friends like the one in the picture, are a treasure to keep .