What is hook guard?

I have seen the name a few times, but don't know it.

I think it's another name for the butterfly guard.  It's where you have both feet (hooks) inside your opps legs.

Oh, I thought it was something else.

There are tons of different names for the same thing.  We call an elevator sweep a hook flip.  Seems like every coach comes up with new names for moves.  We even have a grip called the "happy puppy dog".  My coach was trying to describe how to hold your hands and said it looked like a happy puppy dog.  He then tried to change it to the snake grip to make it sound cooler but it will always be the happy puppy dog to me.  :)