Chile's 3 NOCHES DE UN SÁBADO (3 NIGHTS ON A SATURDAY) by Grupo ICTUS.
Since its premiere in the 1970s, it hasn't been shown again until now. Good music and performances by Claudio Arredondo and Catalina Saavedra. Half of the dialogue is witty, but the other half are common sentences with funny voices (a very basic form of humour). It breaks the 4th wall in a creative way, but the ending sucks.
Since it probably won't be shown in other countries, here's the link to the movie adaptation (if you're interested in checking it out): http://www.imdb.com/title/tt0335489 I'll look for it because I do want to see it.