Ex. 1 - A crotch face is a person born with a strange physical retardation. In this case, Their Genitals are in place of their face, and face in place of genitals.
These are the only retards you are allowed to laugh at, but they are extremely rare, only one is born every year and they do not like to come out of their homes.
Ex. 2 - A general insult for a person being a dick. Can also be used when others are using genital size as insult.
See also Dickhead