LOL. This is such a great question.

Those of us with military affiliation know exactly what it means and were it not for my "keep in PG" philosophy, I would translate it exactly. Instead I will tell you this.

The phrase "Bravo Foxtrot" is like a warm verbal hug between old friends... Friends who can't stand the sight of each other and wish the other one would step in from of a bullet or four or five because their friend did something unbelievably underhanded and conniving. Think of it as a more powerful way to call a person a backstabber...

More literally, Bravo Foxtrot is the military phonetic alphabet's representation for the letters "B" and "F"