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1.
A mong who carries a briefcase. It is quite common for them to wear suits and have hot mums
From the british show 'The Inbetweeners', Will is reffered to as a 'Briefcase Mong'.
by briefcase mong July 06, 2009
 
2.
A phrase commonly used to insult individuals carrying a briefcase and wearing a suit.
Jay: Alright briefcase mong?

Will: I am here you know.
by BriefcaeBoy April 25, 2011