Berlin - It's a phrase that's now crossed into other parts of Germany, but might still be difficult to understand at first, possibly because it drums up no appropriate mental imagery: Ich habe Knast. It means: I'm starving - like really, really hungry. Advanced German speakers will know Knast as a slang term for jail, and though some mental gymnastics can link the phrase with being behind bars with Mordshunger (murderous hunger), that isn't where the term comes from.
Initial investigation will lead to an explanation that it's related to the Hebrew word for a monetary penalty or fine, which broadcaster Deutschlandfunk says is the etymology of the slang for jail. Another explanation says Ich habe Knast is based on a slang term (Knast) for a bread heel (German has as many terms for this as types of bread) but MDR Jump, a public broadcaster in central Germany, says they're both wrong.
Their word expert says it's short for knastern, which is the sound some wood makes when it burns and, therefore, the sound your stomach makes when it's really, really hungry. So saying, Ich habe Knast! means: I've got a rumbly tummy, it just doesn't sound as cute.
And since it's quitting time, Ich habe tatsächlich Knast.