Definitions by Gildey

BSF 

Boston Sports Fan
Someone who cheers for the Patriots, Celtics, Bruins, and Red Sox either by choice or by default (someone who is originally from Boston or has lived in Boston at one point in time).

"You're not watching the Patriots? Just because you're in New York doesn't mean you can abandon your BSF duties."

BSF by Gildey December 21, 2015