German phrase
Den Teufel an die Wand malen.
Meaning
Imagine the worst
When to use it
It means imagining the worst. It is casual and often meant to calm someone down.
Example dialogue
Was, wenn alles schiefgeht?
What if everything goes wrong?
Den Teufel an die Wand malen kann man sich sparen.
You can spare yourself imagining the worst.