The Red Dwarf's computer Holly invented this amazing device in the episode Parallel Universe. It is nothing but a small, orange cardboard box labeled "HOLLY HOP DRIVE". On it are a green button labeled "START" and a red button labeled "STOP". When Lister asked how it works, Holly replied "It's fairly straightforward. If you want to start it, you press START. I'll leave you to work out the rest of the controls on your own."

The device was intended to transport Red Dwarf back to Earth in a matter of seconds and the crew agree to start it so Holly begins the painfully tedious ignition sequence. When Rimmer interrupts Holly's preflight checks, Holly cautions him "the slightest mistake in just one of my thirteen billion calculations and we'll all be blown to smithereens!" He skipped the rest and began the countdown.


At which point he is interrupted when asked where the seven went to... After explaining his blind spot for sevens and a gloomy prediction by Rimmer ("we're going to die..."), Holly starts lower down (at one) and they blast off. Rather than making it to Earth, though, they arrive in a parallel universe, exactly the same as their own with one major difference: genders are exactly the opposite (except for the Cat - his opposite is a Dog).