봉's original meaning is 봉황, a mythical bird supposed to bring wealth and prosperity. So people say 봉 잡았다 when they have unexpected good luck/profit.
The meaning is also extended to refer to someone who gives in/away too much to others because they are not astute enough - i.e. the person ends up becoming a bong to another person.
So 봉 체질 (physical makeup, nature, tendency) means the tendency to habitually fall prey to others.
봉 대접 (treatment) is the way people treat a person who acts like a 봉 (they like to take advantage).
- 쟤는 봉 체질이야 = He easily falls prey to others (in dealings).
- 손님을 봉 대접한다 = Treat a customer like a cow to be milked.
(Try www.tonysweb.biz for hard questions like this)