It is actually saying a made-up word "Grroosss". This is similar to a German word for "greeting", Gruß, possibly referring to the Austrian and Bavarian greeting Grüß Gott that the group would have heard while recording the album in Munich. However, after the song's release, so many people had mi...
I didn't like it the 1st time I heard it. But, now I'm hooked on it. I think this will go #1.