look up any word, like blumpkin:
 
1.
To be pregnant.
It was very embarrssing for Kevin when he got Peggy up the duff, but it served him right for trying to save money by using a flak jacket.
by Dunky Oggins December 07, 2003
 
2.
Pregnant, usually unplanned.
She's up the duff and really confused right now.
by Tsee October 31, 2006
 
3.
Uptheduff

1. The slang term for being pregnant

2. A drinking toast with Duff beer in the Simpsons
Example: She’s uptheduff again

Example: I’ll uptheduff to payday, to dooh
by Dart Hereand there September 23, 2007
 
4.
An expression of great misfortune, expanded from it's original meaning, to be pregnant. The expansion is due to the expression often being the unfortunate case of the pregnancy being untimely and unpredicted.
"When they find all the coke in Mark's desk, he's gonna be sooooo up the duff!"

"Shit, I've got 2 flats and only 5 minutes to get the airport!"
"You are up the duff mate"
by Jack Nicholson February 02, 2006