Michael How do you respond if someone is expressing gratitude by saying "Thank you"? It's probably one of the first things Germans learn in English class, that under no circumstances they may reply by using the literal translation of the German "bitte" ("please"). Instead, valid responses include "you're welcome", "sure", or "no problem".
But we're not in English class here, rather you have the pleasure of being instructed by some of the most experienced foreign language connoisseurs on the American continent, and today we're telling you what Americans say when they want to be informal in this context: "Uh huh". The phrase is most commonly used in situations where one party says "thank you" for a common courtesy like a door being held open, where "you're welcome" would be too much and sound almost silly.
Sometimes people pronounce it almost like "a-ha!" or more subtly as "mmh-hm", both variations are friendly acknowledgements. On the other hand, if the pitch goes down towards the end, and it almost sounds like "uh-oh", then it's meant sarcastically. A single "Huh?" on the other end is a rather sloppy way of telling someone that what he's saying doesn't make any sense. Without the question mark and without the corresponding rising pitch at the end, "Huh" expresses mild astonishment, as in "Who would have thought?". Strictly speaking, none of these expressions will go well if you're in a job interview with the company owner who's wearing his pants pulled up all the way to his chest. In these situations, you'd be advised to resort to traditional idioms to avoid being reprimanded.