Use cloneCollection
http://docs.mongodb.org/manual/reference/command/cloneCollection/
On the target server, run
{ cloneCollection: "databaseName.socialmedia", from: "mongodb.example.net:27017" }
If you wanted to do this on the same server:
db.socialmedia.copyTo(newNameOfSocialmedia)
http://docs.mongodb.org/manual/reference/method/db.collection.copyTo/