What does it mean by "Don't get your panties in a bunch"?
How to use it?

Question

Answer

The  idiom that Australians use is "don't get your knickers in a twist" which means don't get upset about trivial matters.
Person A: Why  are you turning right ? We're going the wrong way!"
Person B: Don't get your knickers in a twist, we'll get there.

Answer

It means, don't get irritated. Said to a man, it's an attempt at a joke, irritation or humiliation depending on the situation.