1) Go to Google Translate
2) Set the translator to translate German to German
3) Copy + paste the following into the translate box: pv zk pv pv zk pv zk kz zk pv pv pv zk pv zk zk pzk pzk pvzkpkzvpvzk kkkkkk bsch
4) Click "listen"
5) Be amazed :)
You could also use this permalink, but it's less exciting. There are many other variations you could try.
Google decided to make it more obvious that this is an Easter egg by replacing "Listen" with "Beatbox".
Here's a YouTube video featured in Google Demo Slam:
{ Thanks, Zachary. }