Time out!

So here is my question. How in the world do you discipline your child when he does something so unexpected and funny? Logan, as usual, was being mean and rough with Summer. So I asked him, "Logan, do you want a time out?" Usually this works great. The few times he has had a time out, he doesn't like it and learns to say sorry quickly. So usually when I ask him this he says "No, no, no!" Well today he said in a voice that sounded so much like mine (with his brows down and his little finger pointing at me) "Do you want a timeout?" I couldn't help it. I just laughed out loud. So, of course, he laughed. But I had to get serious and tell him not to talk to me that way or he'll be doing that all the time. He's already tried again. It wasn't so funny the second time! Oh I love this age!