Usually playing unplugged means either the singer of a band sings the song to just one acoustic guitar or the guitarist plays on an acoustic with the rest of the band sticking to their normal instruments.
When Get the Cat plays acoustic itīs only Astrid who does not change her instrument - how could she? Philipp plays his nice Lakewood acousticguitar, Till plays his hundred year old upright bass and Ralph changes from drums to Cajòn. A Cajòn is basicly a wooden box that you sit on and beat with your bare hands. If you want to learn more, look it up at wikipedia: 
Their acoustic programm holds most of the bluessongs from their electrical set plus some nice tunes that create a nice campfire atmosphere. Itīs great fun to hear them sing harmony! The acoustic side is even more spiced up with a good part of jazz. Of course all songs are originals written by Till Brandt.

 
here you get to the acoustic myspace site of Get the Cat, the songs were recorded live at the Bluessession in the Kattwinkelschen Fabrik in Wermelskirchen.