Fulano de Tal

Things Cubans (and by default Americans of Cuban ancestry) say which make people who understand Spanish look puzzled: "Fulano de Tal" which was and still is, and will always be a puzzle to me, since it means something like "John Doe"... cough, cough... except that Cubans have another guy named "Mengano"... so it is "Fulano y Mengano" --- what??? It's like two made up names that cover Tom, Dick, Harry and Jane all at once...

And I am told that there's also even two more characters: "Sutano" and "Perengano."