Ok, you understand it as "So groß und [du hast] noch’n Schnulli?". I was hooked on the interpretation "So groß und [du bist] noch’n Schnulli?" In the given context, your interpretation is probably right.I don't think so. The heading reads "Die 26 nervigsten Sprüche von Eltern".
"So groß und noch’n Schnulli?" is a typical comment when adults think a child is too old to still use a pacifier.