During play, press Shift + ~ to bring down the console. Now type in the following
and press Enter to activate:

biggerpockets  Infinite ammo
casual         No clothes
doubleshot     Faster rate of fire
hotstuff       AI smarter
iamleet        Win Mission
johnwoo        Slow motion
justin         AI never surrenders
nc17           bleed more
noshades       Night becomes day
rabies         Rats become rabid when shot
swatlord       God mode
whosyourboss   Force a teammate to fire their weapon