So my best guy friend likes my best girl friend.
The girl sees the guy as being a brother (I talked to her once and we both said how gross/awkward if would be to date him).

I typically tell them both everything and they do the same.

Should I tell him that she sees him as a brother only?
Should I tell her that he likes her?
I don't want to not tell them, but I don't want to make him feel bad or her feel awkward.
Advice?

Wow. That sounds awkward.
The right decision would probably be to not tell either one about it, I guess... but I might tip my best guy friend that the best girl friend doesn't feel the same for him... just so I could avoid him asking her out and getting hurt.

Very tough decision. I would probably have to say to not tell eather one becuase you dont want him to get hurt and you dont want her to feel awkward.

if i was stuck in that situation i would probably let her tell him. i know shes your bestfriend, but its still best NoT to get yourself mixed up in this. one of them may become resentful. just tell her that he should talk to him...

just leave the two alone. let them solve their problems out. it's between them, so don't get in the middle of it.

I agree that you shouldn't get in the middle of anything. If he or she asks you, don't lie.

Make sure neither gets hurt, but don't just but in.