Weapon lowering
From Halopedia, the Halo wiki
Weapon Lowering
Use
the halo series has been famous for its machinima features such as being able to lower your weapons even though halo 1's weapon lowering was actually a programing error the next two games had specific machinima functions
Halo CE
halo combat evolved weapon lowering (glicth) can be achieved by looking down, your head will keep its general direction and bob slightly when you move the camera up and down
Halo 2
to do the weapon lowerin ((glitch?)oh can it really be called a glitch) can be achieved by pressing down on the d- pad. note: in halo 2 the lowering weapon glitch was actually a programmed function
Halo 3
to do the weapon lowering (we'll call it function now) it is achieved by pressing a helluva lot of buttons
L3 (TEABAG) LB (CYCLE GRENADES) RB (RELOAD) A (JUMP) Down on D-Pad (multi player screen)
the reason it has got really complicated it halo 3 is because of new multiplayer settings