The universal greeting
1 ESPERANTO International artificial language based on words common to the chief European languages, invented in 1887. Totalitarians didn't take to the language and it was banned, most notably in Russia and Germany where Esperantists were executed. The language has 28 letters and, while it hasn't been embraced as an official language of any one country, up to two million people have studied it since its introduction and it has 1,000 speakers today. The language featured prominently in the first two series of Red Dwarf and fleetingly on TV and film.
2 KLINGON Eponymous language of the Klingon race in Star Trek. Marc Okrand devised the language, although actor James Doohan, who played Scotty, devised the original few words. It was first heard in 1979's Star Trek: The Motion Picture and Doohan's vocabulary was expanded by Okrand for Star Trek III – The Search for Spock. The Klingon Language Institute promotes the use of Klingon worldwide. There's even a death metal band called Stovokor ("afterlife") who sing in Klingon.
3 WORZELESE Worzel Gummidge, Zummerset's favourite multi-headed scarecrow, teaches the children of Scatterbrook Farm how to speak Worzelese. Every word of three letters or less ends with "dip" and words of four letters or more end in "zel". Throw in a "wor" after every letter and you can speak the language like a native. G-wor o-wor t-wor-dip t-wor h-wor a-wor t-wor-zel?
4 UNWINESE Probably most famous for his narration on Happiness Stan, the side two opener on the Small Faces' 1968 concept album Ogden's Nut Gone Flake album, Stanley Unwin's unique language graced the cultural zeitgeist of the 1960s and 1970s.
5 NEWSPEAK A simplified version of English featured in George Orwell's Nineteen Eighty-Four as a totalitarian tool by the Party to suppress free thought. Newspeak is now taken to mean any attempt by relevant powers-that-be to subvert unsatisfactory language.