A 'Gwa' is a person with a general chernobyl look to them. They have a recessed chin, overbite, a sharp or overlarge nose, lazy eye and/or usually accompanied by other rat-like features. The recessed chin and overbite is mandatory. They are best determined by seeing a side profile. Its almost like their chin becomes one with their neck. Think of the movie "Gummo" or your typical trailer trash. The defination was created by Jennicartoon.com after noticing the evolving "look" of people. These "gwa's" got their name by basically looking like the only word they could spit past their stonehenge teeth would be "Gwa!"
Holy shitballs! Look at the Gwa's picking through the dumpster! "Gwaaaaaaaaaaaaa!" (then insert laugh here)