Doesn't the chapter provide you some context? The sub-title probably relates to the content of the chapter.
My guess is that it means "You don't have the guts to call me an S.O.B to my face" or possibly "If you are going to call me an S.O.B, you'd better make sure you aren't in front of me when you do".
I have a dim recollection of it having something to do with cutting off contact with people who habitually bring negativity to the lives of others. Perhaps the main title of the chapter would yield a clue?
While the name sounded familiar, I couldn't recollect who Phil McGraw was. I just looked him up and I think fiercediva's suggestion is more likely to be right.