It means Big Fake Friends When your friend told a secret or something really deep of you to another person, that person becomes a "bff" but with the " .
Or maybe she told someone something bad about you
Because bff don't do that u know
Best Fake Friend
what to call your BFF (best friend forever) when they've let you down for god know which time and you're not sure if you want to clear things up or just simply leave them