A person's metaphoric
wang, the size of which being related to his apparent devotion to the environment via principles, purchases, lame t-
shirts and bumper stickers,
etc. "Green" comes from the color commonly associated with environmentalism, and "peen" is short for penis. Duh.
While Ryan greatly enlarged his greenpeen by purchasing a Prius,
Sean's Highlander Hybrid provided a
decent enlargement while also allowing him to keep his
dignity.