"Wait a minute, I never used to be a man!"
Brown was not very prominent in the lives of Lister and Rimmer of Z Shift. She spent much more time with other officers, such as Captain Hollister and Todhunter. Brown ranked between the two officers and had a high security clearance. She was killed along with almost all the crew when the drive plate gave way and the ship was flooded with radiation.
Three million years later, Lister accidentally activated the self-destruct sequence by ordering a snack from a skutter mis-wired vending machine, and Holly pointed out that only the Captain and senior officers had clearance to abort the program. Since they were all dead, Kryten suggested transferring the Captain's mind from his hologram personality disc into Lister's body. Hollister could then use his voice-print and brain scan to convince the computer to override the sequence.
Rimmer and The Cat ran off to find Hollister's disc, but couldn't locate it. Instead they brought the disc containing the mind of Carol Brown, who also had clearance. After Lister's mind was flushed out and stored on a (very small) storage tape, Brown's disc was uploaded into his body.
At first she was disoriented, demanding to know where she was. Rimmer tried to explain, but she insisted that something was wrong and different. It soon dawned on her that she had a male body with male sexual organs, something that came as rather a shock. Rimmer pointed out that unless she shut off the self-destruct, those organs (and everyone else's) would go into orbit around the nearest planet.
Brown used her security code (O1-O1-O1) to order "Abort sequence X1X". The computer paused to verify her identity, but denied her request and completed the destruct sequence. Fortunately, the miswired computer simply gave Lister the snack that he had ordered. Brown's personality was returned to her disc and Lister regained control of his body. (RD: Bodyswap)