Take a powder
Definition 1 of 1
Pro Tip 1/3Idiomatic Use
Understand it's an informal idiom, not to be used in formal or written English. 
In casual conversation, she mentioned she might take a powder before the event ends.
Pro Tip 2/3Quick Escape
Implies a swift, sometimes sneaky departure, often to avoid trouble or discomfort. 
As soon as he saw his ex-girlfriend enter, he took a powder through the back door.
Pro Tip 3/3American Slang
It's predominantly American slang; may not be understood in other English-speaking cultures. 
While living in the UK, he realized 'take a powder' confused his British friends.