It means " I'm F*#ked Up Bro", just feeling super weird.
I was hangin with the boys tonight and we hit about 5 reggies and drank beers all night and i was just #FUB , couldn't walk or do anything.

Just hung out with my friends and got #FUB and chilled all night watchin movies and playin video games.
by smitty ktwon reppin August 20, 2011
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When someone ignores you or regards you in disdain on Facebook - you've been fubbed.
Someone has completely fubbed me on Facebook.
by Precisionista March 27, 2013
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The act of sticking a finger up someone's bum during sex, either with their express request, reluctant permission, or (more amusingly) completely out of the blue.

Applies to both gay and straight.

Consider it a sort of polite alternative, or a beginner's version if you would, of fisting.

It comes from the acronym FUB - Finger Up Bum.
Derivatives like 'to fub', 'fubbed', 'well I'll be fubbed', 'fubstep' and so on are known to exist and are applicable according to context.
"I was having sex with this 8/10 girl yesterday and out of the blue, she starts fubbing me. No warning whatsoever! At first I didn't know what to do, but she was pretty fit so I just rode it out... Fubbed and proud!"
by Gibralteaser November 4, 2012
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Wanted by gang members due to scarcity and value.
The new xbox system was fubbed from Philly to LA.
by JIpod December 7, 2005
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Favorite Un-Biological Sister
OR
Favorite Un-Born Sister

A girl who you see as your own family even though you are not blood related.
We are not best friends, we are FUBS.
by malimalu248 December 11, 2009
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