Best sister/friends
When two best friends are so close that they consider themselves as sisters !
- Pauline and Catherine are really close!
- Yeah! They're BSF s :)
by foreveryounnng May 12, 2012
A bsf means best friend usually, bsf can mean a best friend who is like a sibling to you or just a best friend
by Your_Dictionary April 15, 2019
"Bull Shit Foursome"
Four friends who often go out together on random crazy adventures and day trips.
Let's go out BSFing this weekend!
by Cindy5 January 24, 2009
How low do you hang?
Ball Sag Factor
How's the BSF today?
by FactRzerO August 2, 2003
The cliched phrase every guy tells to a girl when he wants her: Beautiful, Smart, and Funny.
Hey bro, did she say yes?
Nah, I did the BSF way too early
by Kukoo October 10, 2010
Someone who is a BOOB STARING FREAK. Usually straight guys.
"oh my gosh that chick has got a nice rack!"
"YOU BSF!"
by CoolerThanYou32197392183 January 23, 2009