Acronym for "kick the f*ing ball." Literally, something you would yell during a game of soccer
to someone who is staring at an open goal with no defender in sight.
However, in a more general sense, it means that someone is staring at a golden opportunity that can be easily achieved and all they need to do is to KTFB and get an easy win.
passes the ball to Milito inside the penalty box and Robert Green
is off to get some fish n chips! KTFB!!
In life, generally:
Mr. A: That girl is totally hitting on me!
Mr. B: KTFB!!