Brain Freeze!

I love ice cream!  But it's C-O-L-D!  I love to take a bite of it and then say really loud, "It's C-O-L-D!" and then hold up my tight fists by my chest and do a little shiver.  Yes, I can shiver on demand, even when I'm not eating ice cream.  It makes everybody laugh when I do that!  

Sometimes when I eat ice cream, my head hurts a bit.  Daddy says that that's called "brain freeze."  Brrrr!

The other day, Mommy and Daddy were talking about the brain.  They asked me, "JoMo, do you know what the brain is?"

I nodded.  Of course I do!  "Ice cream!" I said confidently.

Why did they laugh?