Shoulder or Messenger?

Derek and I had an amusing conversation last night.  We were telling each other what specific things attracted us to each other in the beginning.  Derek's were very sweet.  One of his reasons was I was studying German (he lived there as a child). 

Mine were a little weird.  The thing that I said that garnered the most attention was that his "messenger bag" attracted me to him in the beginning.  At first he was surprised that a bag would attract me to him (It wasn't really the main thing.  I just remember it was part of his general first impression).  Then he had a problem with my terminology. 

He insisted it was a shoulder bag because it was a laptop bag and he hung it over his shoulder and across his chest.  I was sure it should be called a messenger bag because when I hear "shoulder bag," I think of a woman's purse with a long strap.

So what do you think?  The bag in question looks something like this...