I cannot remember exactly where I read this - it is possible it was in "Where Ghosts walked: Munich's road to the 3rd Reich" by David Clay Large
(It is worth noting that due to the fact that most grain was reserved for making bread, the quality of beer decreased during the 3rdReich)
A fella goes to the Hofbrauhaus and orders a glass of Helles. He takes a hearty swig and practically pukes and spits it out the next second.It is disgusting. "Thats like no beer I ever tasted before" he thinks. "And I've tasted them all"
He puts the glass under his coat and walks out. He contacts a chemist and asks for the liquid to be analysed.
A week letter he gets a letter through the post.It reads: "Herr Schmidt, your horse has daibetes"!
I always use that when I give tours there. Thankfully the beer is much better today