Press "R" for radio then any of the following codes:
 
 PIGSOINK - Max Overkill (Overload Weapons)
 HARMONY - GPS Hellfire
 6969 - Mercenary
 X666 - Kill Teammate
 IMARAT - Invisible
 IMACOW - Time freeze
 LOADME - Reload
 FIXME - Fix Damage
 
 Submitted by edmar.