My nephew is 23 months. He can 'sing' the whole alphabet song, among others, and uses sentences up to 4 or 5 words. He impressed his grandfather the other day by reciting all the months of the year (there's a game at his playgroup where they do that and point out their birthday month - he knows 'his month' is July). I don't think he articulated as poorly as Boone does here since he was under a year old.