a great way of saying.
cows like to do something.
everytime they moo -- they are masterbating, but you can't see it.
"sloppin' the pigs" -- if you get what i'm sayinn.
therefore, cows moo...everytime they see a "hot" ass cow.
moooooooo.. "ahh that bitch is fine."
so they say, "cows moo"