To blatantly ignore orders from a superior. Most often used by U.S. Marines (typically NCO's and SNCO's) to describe what younger Marines are doing when should be working. First used by a crusty old devil dog in the early 1900's by the name of Clifton Bledsoe Gates. Gates would later become the 19th Commandant of the Marine Corps.
Listen you shitbirds, get off your asses and quit gaffing me off!!!

But Staff Sergeant, I would never gaff off your orders?!?!
by Gunner Brad May 12, 2010
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A filthy household which is fuelled by drink, drugs and deep house music.
"You coming back to Jacks chippy gaff after parklife?"

"Yeah mate, can't wait for some balloons and Jamie Jones".
by Chippy_Guy January 11, 2016
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In Dublin slang it means a night of mayhem. Gaff means house, therefore by the end of the night of drinking/taking drugs/ talking rubbish to people you don't know, the house or flat will have been destroyed. You must say it in a grating working class Dublin accent for full effect. Since Dublin clubs close ridiculously early, people are forced to gather in someone's house or flat (often someone they don't know at all but that's not important) and drink and take drugs until a) everything is gone b) they pass out or sometimes c) wait until the off licences open the next day so they can start wrecking the gaff even more.
It was a great night, we wrecked the gaff.

We went to some bird's house in Tallaght, totally wrecked the gaff.
Come over, we're gonna wreck the gaff!
by Lastika May 14, 2010
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half gaff is a Scottish term used to describe a party that has a smaller number of people than a usual one.
Half gaff is defined in the Scottish slang folklore as a party with not enough people to call it a full party. For example a 'party' with under 20 people would be defined as a 'half gaff'.
'Thought it was going to be a full on party last night man?'
'Nah not enough people had to be a half gaff bro.'
by djkt June 2, 2017
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High-quality cloth-backed adhesive tape. Stronger, stickier, more reliable, and generally about 1000x more versatile than duct tape. Also as much as $25/roll. Fixes just about anything and everything and can be used to rig up just about anything on a photo of cine shoot. Has a strong cult-like following among professionals in the visual arts.
Hey - take up the slack in that cord and gaff it to the C-stand.
by Dave "Bulldog" Munson December 9, 2003
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"I was sitting in the Gaff and I had no fucking clue"

Having no fucking clue on a situation or discussion.
May also be used if feeling tired or out of place and not knowing what to do.
Bob - "Do you understand the maths question?"
MC Monty - "Nah Im sitting in the gaff right now."
by MC Monty July 2, 2020
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To let out information that should have been secret.
We just dumped the waste chemicals into the reservoir until we sacked Eddie and he had to bloody go and blow the gaff!
by pidulgi August 20, 2013
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