Hold your knickers

"Hold your knickers" is an idiomatic expression that means to stay calm and not get flustered or angry. It is usually used as an imperative. The expression is used to tell someone to remain calm and composed while waiting for something.

flustered
ADJECTIVE
agitated or confused:
"a flustered commuter"
"I found myself starting to feel hot and flustered"
Hold onto your knickers, girls!

The phrase “hold onto your knickers” is an idiomatic expression that is often used to convey a sense of excitement, anticipation, or surprise. It is typically used in a playful or humorous manner to create a sense of suspense or build-up before revealing something interesting or unexpected. The phrase is often used in informal contexts, such as casual conversations, social media posts, or entertainment media.

It’s worth noting that the phrase “hold onto your knickers” can be considered a colloquialism and may not be suitable for all situations or audiences. It’s always important to consider the context and the audience when using idiomatic expressions like this.
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Save for that winter’s day 71 years ago (and not forgetting the time Victoria Beckham jumped the gap in a Union Jack bus in the 1997 film Spice World, screaming to her fellow bandmates to “hold onto your knickers girls!”) Tower Bridge has been rising and falling without a hitch for almost 130 years.