I think it's reffering to "Nichts wird so heiß gegessen wie es gekocht wird", which translates to "Nothing get's eaten as hot as it get's cooked.".
(I'm German, but I live in the Netherlands. I absolutely love these jokes between you)
'Ober, deze soep smaakt naar afwaswater.' 'Hoe weet u dat, meneer?'
Einstürzende Neubauten - the band, but the word means "a new building thats always in disrepair" (or so I was told)
Einstürzend = collapsing
Neubauten = made of "Neu"=new and "bauten"=buildings