It's like if someone asks you for a piece of gum. People like to say it a lot around it's like a whole mood if someone u don't like tries to talk to u, you sat gtfbtyswyaa!AND THATS ON PERIODT!!.
Acronym for "Get The Fuck Back To Work". Sometimes used as a truncated version of "GTFO and GBTW", but neither necessarily expresses the same magnitude nor the same feeling towards the person on the receiving end of the acronym.
A: "Dude - want to see some furry porn?"
B: "Not right now. We have to finish this project *tonight*."
A: "Hey I found a .jpg of Schwarzeneggerfingering a chick."
B: "GTFBTW, you cock! Jesus..."