n. Phonetic/slang version of the term knuckle sandwich. Often used to make the speaker sound cool, as to enunciate "sand-wich" often takes away from the overall badassery of a threat involving the knuckle sammich.
Give me a hug before I give you a knuckle sammich.
Go make me a sammich, woman, before I give you a *knuckle* sammich!
Damn, that cat just gave me a knuckle sammich.