| | 4AO | | for adults only |
| | 4GL | | Fourth Generation Language |
| | 4rtd | | Four-Resonant-Tunneling-Diode |
| | 5MW | | Five Minute Warning |
| | adidas | | for chicken feet |
| | ado | | flurry of communication |
| | API | | fire |
| | CBJ | | fellatio with a condom |
| | DES | | from |
| | dui | | for |
| | dur | | far |
| | EGBDF | | for remembering notes on a treble cleft music staff |
| | F&M | | Foot and Mouth |
| | F.A.T. | | File Allocation Table |
| | F.B.S.M. | | full body sensual massage |
| | F.D.A.U. | | Face Down Ass Up |
| | F.F.O. | | for food only |
| | F.F.O. | | Funds from Operations |
| | F.O.B | | free on board |
| | F.O.I.L. | | First Outer Inner last |
| | F.R.O.G. | | finished room over garage |
| | F.R.O.G. | | Frequency-resolved optical gating |
| | F.R.O.G. | | Fully Rely on God |
| | F.T.C. | | Federal Trade Commission |
| | f.t.f. | | face to face |
| | F.T.Y. | | Failure to Yield |
| | F.U.C.K. | | fornication under consent of the king |
| | F.U.C.K. | | friend you can keep |
| | f.u.r.b. | | f**k you right back |
| | F.Y.I. | | For Your Information |
|