There is an old saying that says a good friend will come bail you out of jail, but a best friend will sit with you in jail for the night. Well a BFFTW will break you out of jail using a helicopter, just so the two of you can go to a movie together.
The abbreviation for the phrase "Birth Control For The Win."
The word emphasizes the importance of the techniques and methods use to prevent fertilisation or to interrupt pregnancy at various stages, or it can also be used in situations of extreme delight.