Piper seems to love absurdity - she'll look at you with a twinkle in her eyes, say something that we both know is untrue, and then totally crack up. Like this:
Piper (While sitting in our living room): Ready to go home?
Me: You ARE home.
Piper: Bwahahahaha! Ready go home! Hahahaha!
(we repeat the joke for three more minutes)
Piper (pointing at her dad): Have milk? Daddies have milk? Have some Daddy milk?
Us: Daddies don't have milk!
(repeat, repeat, repeat)
Those are her two favorite jokes, right there. The knock-knock phase is gonna be F-U-N, I can tell already. Recently she's added a new one:
Piper (out of nowhere one day): Can I drive?
Me: You can't drive, you don't have a license.
Piper: (with a look like 'Holy Shit, Mom Made a Funny'): BWAHAHAHAA! Don't have a license! (looks at me again, eyes twinkling) Can I drive?
Me: No, you can't drive. You don't have a license.
Piper (laughing so hard she nearly falls over): You no have license! You can't drive! HAHAHAAA!
Not having a license is apparently very funny when you're two. Sixteen, not so much.