Returning the verbal challenge

Retaliation, however justified, will be seen by your
aggressor as an acceptance to fight. From my experience, if
you do not make a hasty retreat at, 'actual challenge',
especially if you do counter verbally, more threats and a
possibly attack will result. A non-counter and immediate
exit on the part of the victim usually results in the challenger
aborting, perceiving the response, or lack thereof, to be an
embryonic victory. Therefore, if a verbal challenge is thrown
do not counter.
If you are approached and are unable to escape, then you
must prepare yourself for fight or flight. If you are in a pub
and you sense trouble, it is my advice to leave that particular
pub and find another that feels less threatening. An ounce of
prevention is better than a pound of cure. At and before eye
contact you should have been in Code Yellow, this will have
given you awareness, not only of the potential situation, but
also of the 'ritual'. In such situations knowledge is power.