Possible Clues:

• Holy cow for Hamburgers?
• Hamburg grr?
• Coblenz complaint
• Cry in Kšln
• "Oh" de Cologne?
• '___ Gott, vom Himmel sieh darein' (Bach cantata)
• Berliner's 'Alas!'
• Günter's gripe
• Karl's cry
• Bavarian carp?