To have a verbal contest over progressively worse mum jokes. It usually goes around full circle before someone gets mummed-out.
Kevin: Your mum's a slapper.
Joe: Your mum is a bigger slapper!
Kevin: Your mum invented being a slapper!
Joe: Your mum wrote the slapper's handbook!
Kevin: Your mum followed every move in the handbook!
Joe: Are you challenging me to a mum-off?
Kevin: Your mum likes a challenge... etc
Joe: Your mum is a bigger slapper!
Kevin: Your mum invented being a slapper!
Joe: Your mum wrote the slapper's handbook!
Kevin: Your mum followed every move in the handbook!
Joe: Are you challenging me to a mum-off?
Kevin: Your mum likes a challenge... etc
by rob1982 January 3, 2013

by Debskelly1985 March 19, 2023

Here’s a sentence using "mouth off":
She's always mouthing off about how much better she could run the company herself.
She's always mouthing off about how much better she could run the company herself.
by Arminkshipper August 5, 2024

When you’re super faded and you got cotton mouth and your lips are dry and you gotta lick em to keep em hydrated
by StainboyP August 22, 2021

by C.B.Brown June 8, 2023

Taking a piss off the Hollywood sign either is protesting the perfection wanted of people or physically urinating off said sign.
Man:”I went and got a drink.”
Man 2: “Oh no.”
Man: “Yeah I ended up Taking a piss off the Hollywood sign.”
Man 2: “Protesting?”
Man: “No... literally.”
Man 2: “Oh no.”
Man: “Yeah I ended up Taking a piss off the Hollywood sign.”
Man 2: “Protesting?”
Man: “No... literally.”
by Actually It Is *insert thing* September 17, 2019

by CurvaceousGorilla June 5, 2021
