|1.||S or F|
It means Suck or Fuck, referring to sex, of course.
S or F means suck (oral) or fuck (...yeah)
|2.||S or F|
1. A prudish way to refer to sex.
2. A word used to talk about sex when sheltering parents are afoot.
Cheerleader: "So what did you do with that guy last night?"
So-and-so: "Well...(So-and-so's parents walk in)... Just S or F.