Comes from the expression, "Watch Out," as in "Get Out of My Way".
Comes from the expression, "Look Out", as in "Get Out of My Way".
Sometimes all three will be used in quick succession, however, only in the order as seen in the title of this entry.
(Commonly used in close situations when somebody's body physically blocks the speaker's access to something small. Not to be used in urgent situations where the addressed must dive out of the way.)
Pushy Bothersome Person: Chout, cout, lout, mofo^!
Innocent Person in the Way with No Clue Where the Pushy Bothersome Person is Trying to Get: Huh?
Pushy Bothersome Person (Continually poking the other): Chout, cout, lout, mofo! Don't you understand english? Go read the Urban Dictionary! Then you'll be dope* enough to understand the reasoning behind the spoken word.
^See Mofo for definition.
*See Dope for definition.