What does "Don't get your knickers in a knot" mean?
It means do not get too upset or worried about something. It is often teasing, but can sound dismissive if the other person is already frustrated.
The saying in a sentence
The saying
Don't get your knickers in a knot
Example
Don't get your knickers in a knot, it's only a game.
When you use it
Use it as light teasing between mates who know each other well and are already joking about a small problem.
When you do not
Avoid it when someone is genuinely upset or raising a concern. Telling them to calm down this way may make things worse.