Two word sentences

Keagan's vocabulary is expanding every day and he is really starting to "parrot" what we say. He is also doing his own two-word sentences! The one we've heard the most the last couple of days is "More outside" because it's been cold and we haven't gotten our fair share of the outdoors. He also says "No bus" or other "no ___" with some other noun. He's really into playing "bye-bye" with toys which involves hiding them behind his back, so he now says "Bye-bye truck" (or other toy name). The really cute phrase he does when he's on his play phone is "I _know_!" I'm pretty sure he has no idea what that means, he's just heard me say it.