It’s an acronym standing for Back Of Hand On Forehead. It goes back to the early silent movies where melodrama was the
order of the day and the back of the hand on the forehead was used to indicate distress. Now, however, it is applied to those people, male or female, who are complete drama queens and who treat a small setback or minor difficulty as if it was the
end of the world. In short, it is the epitome of overdramatic
exaggeration.