American culture, even in its most rigidly segregated precincts, is patently and irrevocably composite. It is, regardless of all the hysterical protestations of those who would have it otherwise, incontestibly mulatto. Indeed, for all their traditional antagonisms and obvious differences, the so-called black and so-called white people of the United States resemble nobody else in the world so much as they resemble each other. [Albert Murray, "The Omni-Americans: Black Experience & American Culture," 1970]
The mule combines the strength of the horse with the endurance and surefootedness of the ass, and is extensively bred for certain employments for which it is more suited than either; it is ordinarily incapable of procreation. With no good grounds, the mule is a proverbial type of obstinacy. [OED]Properly, the offspring of a he-ass and a mare; that of a she-ass and a stallion is technically a hinny. Used allusively of hybrids and things of mixed nature. As a type of spinning machine, attested from 1797 (so called because a hybrid of distinct warp and woof machines). Meaning "obstinate, stupid, or stubborn person" is from 1470s; that of "narcotics smuggler or courier" first attested 1935.#1 on the side and don't touch the back
#6 on the top and don't cut it wack, Jack
[Beastie Boys, "Mullet Head"]As a surname, Mullet is attested from late 13c., thought to be a diminutive of Old French mul "mule." Cf. also mallet-headed, in reference to the flat tops of chisels meant to be struck with a mallet.