At the end of the finale of Psych season 6, called "Santabarbaratown", Gus and Shawn have an exchange wherein Shawn says, referring to Dahlia Twon, "his sister, his girlfriend, his girlfriend, his sister", to which Gus responds, "...It's just Santa Barbara". I know that many Psych episodes (especially those of season 6) often parody or reference other works. It seams like this is what they were doing here.
What were they referring to?