STFO has been used by many different companies to help motivate sale's Rep's but since the early 80's G. Smith and M. Amoroso made this THE word among "Speakermen". The phrase STFO is used in conversation amongst "Speakermen" to help motivate each other to sell more set's and make as much money as humanly possible in a work day.
ie: "Dude I just slammed this one fucking hit for like $550 on a double set. Alright I'll talk to you later bro. STFO!"