Nammar Grazi are not interchangeable.

co_worker - one with whom you share an employer; a competent fellow human being, gainfully drawing a paycheck along with you.

cow_orker - one who, while they share your employer, is otherwise so useless, actively subversive, or sociopathic that their time would seemingly be better served orking cows.

(note - there is some debate as to what, exactly, "orking" entails, but it is generally assumed to be at least as bad as the worst thing you are currently imagining based on how the word sounds)
dos cow_orker - while normally defined as one who orks cows, also has a second less popular definition: one who orks *like* a cow.

As cows only ork other cows, the act still involves orking a cow. The distinction is subtle and easily lost, but it is this - every depraved thing you've already imagined, but with cud and gas.
Added a la Albert Also, please do not confuse these with c_o_worker. A c_o_worker is a green, leafy plant who does not draw a paycheck from your employer, but works alongside you to make the air pleasant and breatheable. It is generally agreed that one c_o_worker is worth ten cow_orkers. 080105
mustard i think you are the perfect man

you love good weezer

you have chest hair

you are short

your voice is magical

you have a girlfriend

fall in love with me someday, it will be fun
what's it to you?
who go