A common British variation of the American idiom 'yo momma' - usually used as a retort when one is insulted.
"You're such a big bell"

"Yer Mum's got such a big bell, I know 'cos I let it penetrate my ass."
by Tom Preston September 02, 2004
Get a Yer Mum mug for your buddy Jovana.
One annoying line invented by Tony Walsh (aka TDW) which was variation of yo mamma but with an British style to it. It also makes you feel like an idiot saying it as well.

Also managed to appear on Kerrang's Trash Idol.
Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum! Yer mum!
by Chris Ridsdill November 21, 2003
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A term used by 9th graders with knockoff AirPods and cheap vapes
chad: yer mum gae
garret:shut up and let me borrow ur juul
by Thisistheonlytimeillmakeadefen January 24, 2019
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used to make ur friends mad XD
hey jacob whats ur favorite type of burger?

jacob: yer mum
by ria__ July 07, 2021
Get a yer mum mug for your grandma Nathalie.