Play as any infantry unit.
Go into a modified stance (ie: in between sitting with weapon drawn and crouching; The low crouch)
Hold down your sprint key while moving (In this case, SHIFT)
attempt to crouch toggle (In this case, X)
Watch your character take a dive to the floor. (Not sure about rifles, but with a pistol drawn, your character dives to the floor and then stands all the way up.)