Up the duff
Definition 1 of 1
Pro Tip 1/3Slang Term
Used informally among friends or peers; not suitable in formal contexts like business or academia. 
I heard from Ellie that she's just found out she's up the duff.
Pro Tip 2/3British Origin
Known mainly in the UK and other English-speaking countries may not be familiar with it. 
When I used 'up the duff' in America, people didn't understand me.
Pro Tip 3/3Casual Language
It usually carries a casual or humorous tone, and may be considered impolite in serious situations. 
My sister announced she was up the duff at the family dinner, and my grandma was not amused.