to hate the phrase "don't get your knickers in a twist"?

[StealthPolarBear]

It means "you have a strong opinion about this. I do not. Therefore I am going to mock you". Why can't people just accept that other people care about things they themselves may not?

PS I myself on this thread am wearing lovely smooth untwistey knickers

My nan says this when I have the cheek to be offended when she calls me fat/says my hair is shite/criticises my parenting.
YANBU!

YABU. I used it on several occasions to dissolve tensions between teen girls on US Summer Camps. They think it is the funniest thing, helped greatly by my "cute British accent"

hmm yes saying it in a funny way is one thing. But I often see it used to mean "you are overreacting" in a sort of belittling way. If you disagree, fine, explain why. But that is just a cop out IMO