A name given to a kind, warm hearted, gentle person who loves his Eagles-Phillies-Flyers but yet, in a wink of an eye, will rip off your head and shit down your throat when his team loses to any New York team. The nickname is extended by his neighboring New Yorkers who work/live among "Bill" in New York. These same New Yorkers have lost many a close family member who were once a Met, a Giant, and/or a Ranger fan by the above-mentioned beheading and following messy excretion.
Billadelphias drive their cars with an "Eagles" bumper stickers while stuck in Long Island traffic near their N.Y. home.
by Billadelphia100 February 04, 2010