too kid

I was visiting at my sister's place and enjoying feeding my little niece her bottle.  During this time I was discussing with my nephew that his other Auntie's dog Bailey was coming over to visit in a few minutes.  This is what the rest of our conversation was:

Nephew: You have to help me get the gate, so Bailey doesn't go upstairs.
Me: I'm feeding your sister right now.  I bet you know how to do this on your own.  Just turn on the light before you go down the stairs.
Nephew: Yea!  (He starts to walk toward the basement stairs and turns around...) I can't do it!  I'm too kid!