A term for fans of the Canadian actor Nathan Fillion who currently stars in the ABC hit TV show Castle as the mystery novelist Richard Castle. Another term would be Fillionaire. Fillion is also known for playing Captain Malcolm "Mal" Reynolds in the sci-fi TV show Firefly and movie Serenity and Captain Hammer in the online web-series Dr. Horrible's Sing-Along Blog. Every Fillionite knows how double rainbow Nathan is and will always support him.
Having so much money, you can't count it, nor would you need to. May imply a blase attitude about the money, or sometimes the lack of intelligencenecessary to keep track of it.
"So your friend just went and bought you a new tractor?"