Borrowing some Cash

I thought I'd let you borrow some "Cash" to bring a smile to your face - he's always bringing a smile to mine...

I went the other day to get him from his nap (he still calls for me from his big boy bed). I sat on his bed and gave him a hug.
Me: Guess who's here, Cash.
Cash: What?
Me: No, guess who's here.
Cash: What?
Me: No, not what, who?
Cash: Who's who?