It derived from the male-dominated sport of spotting and admiring a woman's cleavage or observing those upper-chest-advantaged ladies who are out in public and proud of their endowments. Men would spot the 'boobs' and then 'swoop' past for a better view.
Henceforth, the sport became known as swoobing.
Technical note 1:
Women are known to swoob on other women purely for comparison purposes and/or hate/admiration, while men do it purely for the love of the sport.
Technical note 2:
The sport of swoobing does not condone the verbal/physical harassment of women. It is a non-verbal and non-contact sport.
Technical note 3:
Swoobing can merely involve the subtle suggestion to one's friend to check out a potential 'swoob' forthcoming, or the mutual silent acknowledgment between 'swoober' and 'swoobee' of her great swoob attributes.
"You missed out on all the swoobing playboy. So much swoobing!"