Socially awkward bunny.

This is Simon being a bit pushy with his need for River's attention.  He'll see her cleaning and immediately go over and shove his head under her face so she'll start cleaning him instead (sneaky bun).  This time, he almost knocked her over in his eagerness.

After repeatedly following her around and interrupting her cleaning, River started to get annoyed and hopped across the room.  Simon, oblivious as always, decided it would be a great idea to nose-bonk the side of her head to get her attention.
I can only liken this behavior to a small child repeatedly saying, "Mom.  Momma!  Mum!!  MOMMY!!!" to get their mother's attention (usually for no reason at all).  Just replace all of the 'mom' variants with 'River' and that's what Simon was like all day.  Sometimes the little fella is a bit needy.