GMM 

Short for Good Mythical Morning.
A daily internet talk show on youtube created and hosted by internetainers Rhett McLaughlin and Link Neal.
Usually including challenges, tests, "will it"s, facts, famous guests or sketches.

"Dude did you watch today's GMM?"

"Yeah man of course I did , It was a 'will it' episode."

GMM by ella-smella-della-ding-dong April 1, 2016

GMM 

Good Mythical Morning. That show on YouTube with those two guys who do crazy ass shit for views.

Girl 1: Hey, you like GMM?
Girl 2: No, those guys suck dick for views
Girl 1: Bitch, I will cut you if you say that again
Girl 2: Runs away crying

GMM by cyanidedreams December 29, 2015

GMM 

The hellish assignment given to students attending the Maine School of Science and Mathematics. It usually consists of eight or nine problems and requires many hours of useless work with 2 to 3 other people.

Margaret: Are you going to start working on our GMM?
Trevor: OH SHIT! That thing is such a bitch.

GMM by Quigsley March 23, 2010

GMM 

Grown MAn Music Clique of Stat Quo, an up-and-coming Atlanta Native. As heard on Young Buck's ''Walk with Me''

GMM's My Muthafuckin Squad, Nigga
They Be Cuttin' Them Mo' Fuckin Checks Now,
I Ride Big Nigga, I Got My Thang Danglin Nigga
And I Gotta Big Thang Out My Balls, Ya Understand Me
Dre And Em'll Feel Ya Man, They Gotta Love Niggas
Let It Be Known That Oscar Defined GMM Music Before Anyone

GMM by Oscar December 3, 2004

GMM 

Got me mad. Usually used in slang, for expressing the anger in which someone has caused.

My brother ate all the food, gmm!

GMM by UrbanSlang12345 September 8, 2016

GMM 

GMM (granny mob massive) a gang of school girls that belittle you with their massive tits.

Granny Mob Massive was more than that. Rebecca and crew dem didn't like our silly boy behaviour in school and thought we were immature so we nicked named them like old granny's who don't like a laugh. So I had my first wank over the GMM.

GMM by Jimbobwally July 25, 2019

GMM 

GMM=gorgor's muimui

Gor gor's muimui=wileen=piggy#3

GMM by wileen November 10, 2003