PG-13 is something we all automatically attribute to childhood. The age where your still a kid, but old enough to do a "Lil Bit" of adult shit. Remember the first time you went to the show without parental supervision? You probably went and seen a PG-13 movie. The context in which I use PG-13 is similar, but different.
A Pg-13 movie contains mild language (Little to no foul language), No nudity or sex NO REAL ACTION! Now think of some of the people you encounter everyday. They're vocabulary sucks, it may be explicit, but it is real basic. They get little to no action. Which in simpler terms "No Pussy". Or they act scared of the opposite sex, just like the shorty in most PG-13 movies.
The term ecompasses a variety of things. Remember the experience I described in the beginning of the average teen? Some grown folk still engage in the actions of the PG-13 movie seekers. PG-13 is meant to be a joke, but its also a wake up call. Put that shorty shit behind you. Lets GROW UP!