I think I have mentioned the orientation week for international students and the "translation" of American phrases we have learned there. Some of them were:
"How are you?" - "Hello."
"Let's have lunch sometime!" - "Mh, you're a nice person, and we might have lunch... some time... not now!! Maybe in... like... a few months?!"
Probably the same happens in Germany, but if you have to understand another language and deconvolve the meaning with some cultural code, it's not alway straightforward what people mean and I was thankful that I talked to others about it.
There are theories about why Americans try to be very polite; one of them says that so many cultures have to live together without conflicting that you try to be friends with everyone. At the same time, a lot of people come and go, so you have to have an easy, open and friendly way to communicate (and to make new friends).
Continuing the phrases from above:
"I'll think about it." - 99% for "No!"
"You might consider doing xyz." - "I encourage you and you actually should do xyz."
"I don't support it." - "I am absolutely against this."
When you tell someone you study physics and you get the reaction:
"Ooooh...". - "Mh, that's difficult, let's switch topics. But no worries, I won't be too social with you."
"I would love to go!" - "That's nice; I might consider to go."
"I'm okay." (Be careful: This is not "I'm fine", thus usually, something is weird or stressful - that's an important one!) - "I'm not okay."
"This is interesting / has a particular property." - "It's wrong or off or it doesn't taste well."
"We should go and do x sometime!" - (That's similar to the lunch-date:) "We might do x sometime, but ... mmh..."
"Your handwriting is beautiful!" - "Yay, I can read it!!"
