Groinal attachments could also be used for simulated sex by humans whilst inside adult artificial reality games. Lister wore his out in three weeks, even though it had a lifetime guarantee. ("Gunmen of the Apocalypse")
On mechanoids, this item appeared as a long tube attached to the groinal socket of the mechanoid. It could have a vacuum cleaner, egg whisk, hedge trimmer, buzzsaw or power drill attached to it (and, it is implied, other attachments).
The artificial reality sex attachment appeared simply as a box around the groin area.
The egg whisk was used to stir Lister and The Cat's tea aboard Starbug when Kryten's behaviour protocols had been deactivated. He did not realise just how inappropriate this appeared. ("Tikka to Ride")
In Series VIII, Kryten is classified as a woman due to a lack of genitalia, distressing him to the point of building an artificial penis called Archie. Evidently, the staff of The Tank never observed Kryten vacuuming...