FAB is a stylized acknowledgment used in radio communications, standing for Fully Advised and Briefed, or sometimes just serving as an emphatic Roger. While popularized by older science fiction television, it found occasional use in real-world police and amateur radio dispatch to confirm that instructions were received and understood.
Heard on the job
Control, this is mobile three, FAB on that last directive, we're heading there now.
Also heard as
- fully advised and briefed