From the Latin 'Mandemulus', meaning a collection of less than reputable characters.
Man One: inviso illa mandemulus!
Man Two: yeah mate, safe, innit.
by Poetic Edda July 20, 2010
A mandem is an association to a group of friends/gang/family, most popularly used by roadmen
Guy 1. What were you saying about my name
Guy 2. Go away or I'll get my mandem on you
by Mcsmally October 8, 2019
Like bruv, mate, friend (informal)
'you ain't mandem'
by divergentgirl March 24, 2015
A hoard of pikeys who go around doing chavvy behaviour. Typically proletariat these underlings try to terrorise the streets of cities with ASBOesque behaviour. Often being very 'try hard'.
Charles: "James look at those hooded youths"
James: "Youths? They appear to be are age?"
Charles "You know what I mean, pikeys, rif raf, underlings, proletariat."
James: "Yes, they seem to have formed some kind of mandem"
by Winnie A June 4, 2011
it means a group of friends ffs!

all you trolls grrrr :D
me and my mandem are going out to rip it up... lol
by Phatdanny July 8, 2011
The replacement of a female tandem partner with a male counterpart in a motorcycle stunt. 2 men 1 bike... Mandem
Guru and Steve Rocked the longes mandem spreader ever!
by Tony Levesque July 11, 2008
A term mainly employed little urban shits to describe groups of other dickheads. Very cringeworthy to hear this if you arent interested in their way of speaking.
'yo bruv you seen dat man... literally... brap'
'yeh e wiv dat dem mandem innit... '
by tom healey December 17, 2016