FNSF 

Friend Not-So Friend. Two people who are not in a relationship but have mutual affection towards each other.

“Are Jake and Amy dating?”
“No! They’re FNSF, they’re just vibing.”

FNSF by Jackendren October 24, 2020

FNSF 

Friend Not-So Friend. A bond between two people who are not in a relationship but having mutual affection towards each other.

"Are Jake and Amy dating?"
"No! They're FNSF, 'cause they're not official yet."

FNSF by anonymous October 24, 2020

fnsf 

someone who spends their friday nights at home online

guy 1: hey! where were u on friday nite?
guy2: umm, just at home on WOW/fb/myspace
guy1: ur a fnsf (friday night sad fuck). hahaha sad fuck.

fnsf by binkyj December 9, 2008