A catchphrase uttered by members of a rap label named G-Unit which is headed by rapper 50 cent. The catchphrase is often recited in an aggressive manner with an emphasis being placed on the 'NIT' of word 'Unit' towards the end. It is supposed to convey a don't-mess-with-us-coz-I'm-a-gangsta attitude. Supposed to. The rapper known as 'The Game' might disagree.