Kryten's manufacturers, DivaDroid International, saw little use in giving its otherwise male creation any genitalia, since he did not need it for any practical purpose. Only those droids designed for work on Italian starships were issued with something they could stand around holding like their shipmates. (RD: Pete II) Lister described Kryten as "a bit like Action Man in that department, just plastic underpants and a trademark". (RD: The Last Day)
When he was sentenced to 2 years imprisonment in The Tank, Kryten was given a medical examination. Since he had no exterior sexual organs, he was classified as a woman and sent to the women's wing with Kochanski as his cellmate. (RD: Back in the Red III)
Dismayed by the humiliation and boredom caused by having to watch the other women exercise and shower, Kryten determined to prove himself as a male. He undertook to build himself a penis from an electron board, a toilet roll, some sticky-backed plastic and an Action Man's polo neck sweater. He named his new penis Archie.
Kryten usually kept Archie in a small cage in his cell and treated him like a pet. He taught Archie how to jump through a hoop, although why he did this was a mystery. When Archie escaped from his cage, Kochanski mistook him for a mouse and tried to lure him out from under her bed with a piece of cheese. Kryten found her on the floor of the cell trying to scare the mouse with a broom handle. He explained that it was really his penis, something that Kochanski thought she had misheard. Kryten tried to recapture Archie with a bucket, but Archie fled into the prison. Kochanski comforted Kryten with the fact that, since he now had no control of his penis, he had indeed become a real man. Kryten was very proud of hearing this.
Archie eventually found his way into The Cat's pocket and fell asleep. When The Canaries were sent to apprehend the Tyrannosaurus named Pete, Archie woke up and tried to force its way out of The Cat's clothes. Rimmer and Lister were astonished by this and demanded Kryten explain who Archie was. Kryten placated them by saying that his penis had escaped. It is unknown whether he recaptured Archie. (RD: Pete II)
Behind the scenes
All the scenes featuring Archie were written and shot for the episode "Cassandra", but were cut for time. They were then pasted into "Pete II", where they were subtly adjusted to fit the plot.
A prop was produced to show Archie, but it moved with such speed that it is impossible to discern its appearance. This was perhaps a perfectly reasonable state of affairs.
The scene where The Cat feels something trying to escape his body and burst out is a homage to the classic science fiction film Alien, in which a similar fate befalls Kane, played by John Hurt. The effect was produced by pushing a stick up Danny John-Jules' trouser leg into his shirt.