The term derives from the fact that Persians have extremely hair ass-holes and it is well known that simply wiping after a shit will in no way clean the ass-hole to a reasonable level. Therefore they are forced to shower after their shits to ensure cleanliness.
--I know, they're Persian.
--Jesus, that man has so much chest hair!
--I know, he's Persian.
Stupid Persian Lady with big mouth and ears: If you hate Persians so much, why do you shop here?
Persian Woman 1: I AM PERSIAN! YOU ARE THE TYPE OF PERSON WHO WRECKS OUR CULTURE! YOU ASSHOLE SHOULDN'T BE LISTENING TO OTHER PEOPLE'S CONVERSATIONS! CUNT!
The persian is unique to Thunder Bay, Ontario Canada, the only place where they are known to be baked.
2) You're Iranian, not Persian...unless you were born there before 1935...get over it...