When Michael thinks he's had enough of something he says "Finished!" If you say "Finished?" He says "OK!" with a tone of agreement that says he's pretending "finished" was your idea in the first place.
He started saying 'thank you" quite early - we loved that. Now its "thanks" as he takes the toast or bottle or whatever. No fuss, just 'thanks" and on his way.
When he see the ABC logo on a book or video now he says "SHOP!" because he pointed to it downtown the other day and Elf said "That's the ABC Shop".
Also - when Marcus bellows something to us from the other end of the house, Michael knows the correct form for the occasion. "OK... COM-ing".