Meaning: fist bump that shit. Use: invite to an fist bump when something is extremely awesome.
Dude: I just got 98% on my maths exam, and I was fucking high!
Other dude: FBTS!
Fucking Behind The Scenes
A term used towards a couple that pretends to hate each other in public, but it's obvious they're fucking. This term can be used towards people you know in real life, or ships from TV, books, or movies.
Rachel: Hey, did you see Aubrey and Zack undressing each other with their eyes today?
Adam: Yeah, they're totally FBTS.