It takes one to know one

In the middle of the night
If I call to her just right
Mammy feeds me, just for fun,
And loves me when the feeding's done,
And we play at patting faces
And at baby girl embraces
And at smiling at each other -
I grin for smiling from my mother -
And at last she makes me rest
Because it's really for the best
But secretly, she'd rather play
If she wasn't sensible today.