It means "Designated Ugly Fat Friend". They don't have to be any of those, but that doesn't mean they don't have friends more attractive than them. The DUFF is basically the least attractive one in the group.
"She's cute, but her friends are hotter. She must be the DUFF."
"He's the youngest in the team and acts as the Gatekeeper to the rest of the team. He's a DUFF."
"That teacher is being left out from other conversations... He's a teacher DUFF."
"He's the youngest in the team and acts as the Gatekeeper to the rest of the team. He's a DUFF."
"That teacher is being left out from other conversations... He's a teacher DUFF."
by WattpadBlogger September 21, 2017
Get the DUFFmug. Mickey Duff was a well known boxing promoter whose name is now universally used as rhyming slang for marijuana.
Mickey Duff = Puff
Mickey Duff = Puff
by Loftier January 23, 2021
Get the Mickey duffmug. The glue to a friendship. She/he will always support there friends no matter what. She can be a pain in the ass but everyone still loves her/him.
by ofiherjonfoqe[h November 5, 2018
Get the DUFFmug. by jayquan24 September 13, 2020
Get the dorcus duffmug. 
