The original title card of this movie reads something like "Nøken Tisdøg" (the spelling of a few characters had to be omitted because IMDb do not accept them), which means "Nude Tuesday" in "Zobftanlik," a form of gibberish invented specifically for the film. "Nude Tuesday" is one of the rare films that uses an entirely fictional language for all its runtime. The title "Nûde Tuesdäy" (here I had to make another omission) is an English adaptation of the original, following the Zobftanlik resource of writing vowels and consonants according to different spellings in other languages.
This said, there is not much originality in this movie about a mature couple that goes to a retreat with a group of persons who want to add some "fire" to their sexual lives. I did not find it very funny, rather a bit boring, with tired situations you may have already seen in better films.