Referring to either the act of sex or calculus depending on the circumstance. Sometimes purposefully ambiguous.
Guy 1: I did a lot of rigorous activities over the weekend.
Guy 2: Really?
Guy 1: Yeah, but I'm still screwed for the calc midterm.
Short for fucking bitch. Usually used without an accompanying sentence. Sometimes used to insult someone without them knowing. SPronounced: Eff-bee
Guy: Do you want to go to prom with me?
Girl: No, so stop asking me every day.
Short for filthy mother fucker. Usually used to express disgust towards a person. Pronounced: Eff-emm-eff
Guy 1: Hey did you do rigorous activities this weekend?
Guy 2: FMF.