You often hear people say that Danish is a difficult language to learn; a more positive attitude would be to call it challenging. Some of the most obvious challenges in learning Danish as a foreign language, you will find in connection with pronunciation of vowels, in colloquial speech acts and in idiomatic expressions. On the background of more than 20 years' experience of teaching foreigners Danish I will present and discuss problems (or challenges) in pronouncing the Danish front vowels, problems using the most adequate speech act in everyday interaction, and on differences between idioms of two different languages (Danish and a foreign language) and the misunderstandings that are connected with that. The focus will be on authentic examples and examples from own teaching material.