A fruit machine was a device used for gambling.
In 2013, Nyssa won on one in the Pescadorian, having used a pound leant to her by Tegan. After Turlough enquired as to her system, Nyssa explained that she had "observed the algorithmic responses of the machine to the last three players" and that it was "all perfectly simple". The Fifth Doctor told her to remind him never to take her to Las Vegas. Turlough said he wanted to do exactly the opposite. Nyssa returned Tegan's "deposit" to her. (AUDIO: Eldrad Must Die!)
Adam Colby told Thea Ransome that he considered Dr Fendelman to be as "crazy as a bed bug", adding, in reference to the doctor's time scanner, "he actually believes that he can see into the past with that electronic fruit machine". Thea was more appreciative of Fendelman's prowess. (TV: Image of the Fendahl)