German Beer Purity Laws
I was working near Frankfurt and staying at a hotel my employer was paying for. The waiter serving me breakfast was the same guy who'd been my bar tender the previous night. I mentioned I didn't have a hangover, and ascribed that to the 1516 German Beer Purity Laws because I'd downed about 15 pints and still felt fine.
He replied, "It might be that. Or it might be because you were drinking non-alcoholic beer all night"
"Why didn't you tell me?"
"You seemed to be enjoying it."