From Norway here. We have a lot of different idioms that are absurd in other languages.

1. "Skjerp deg" - literally means "sharpen yourself up". It is something that you tell someone when they are acting bad
2. “Takk for sist” - Thanks for the last time is something that you tell people you haven't seen in a while. But there is no time period and you can say this word no matter how long ago you met the person
3. Glad i deg - means glad in you. Is a middle thing between "nice to meet you" and "love you". Love you is too much to tell your friend, so you use this word instead