"Wise Guys" are a German a cappella group, i.e. they sing without musical accompaniment. There are 8 members in total, some doing main vocals, and others doing accompaniment or "background noises". They are also a comedy group. Although I don't understand German, I'm sure that someone who did would find it quite amusing, judging by their popularity in Germany. The Wise Guys have created some rather impressive songs, such as "Der Letzte Martini", which as I understand it parodies James Bond. Another song, "Root Beer Rag", shows their versatility and exceptional skill. This song doesn't actually have any lyrics. Even if you don't speak or understand German, these guys are definitely worth listening to, and you'll be impressed by their harmony and talent.